Well..wrong on both accounts but i didn't want to give advice about this part because changing it is a huge pain and I'm sure there is a better way. Anyway, here goes:

More racial edits, you need to flag all attacks as power attacks and adjust the stamina cost to your liking. This means changing every damn entry for every playable race, also you need to change the "powerattackchance" gamesetting to 100. (Not entirely sure on that part, but it's a safe bet if you don't NPCs won't attack as often as they should, I just did it to be on the safe side since creatures have their own powerattackchance variable that i did not have to touch). This will effectively prevent you from being able to attack or bash with no stamina. No luck on bows yet however.

I took it one step farther but this is where you really gotta be careful or you can screw your game up bigtime:

In the animations tab, you can edit the characters animations to add the condition of needing a certain amount of stamina or stamina percent in the powerattack roots.

Since I use highly modified race starting stats I decided to actually use both conditions like this:

GetActorValue Stamina > 50 AND
GetActorValuerPercent Stamina > 0.10 (AND)

In order to use this attack you need to have at least 10% max stamina and 50 stamina. This way you can't even use the powerattack unless you meet both these conditons.

Notice that 0.10 is considered 10% (annoying since this is NOT how all percentages are calculated, "GetRandomPercent" actually looks for the whole number, not the integer)

Lots of customization options here. Just gotta mind your step.

Again, no SKSE required

I would suggest asking around a bit before going this route, it can be risky, takes a while and is most definately not something you want to get into if you ever plan on releasing the mod to other people. But for me, it has been quite successful (as long as I load it last of course). My full "mod" have overwrites on everything from perk trees to leveled lists to movement types to original spells. If I ever released it as a mod for others there would be utter, complete chaos.
A bit tempting really, lol.

Thanks for that!
The question obviously is, if I flag all attacks as power attacks, would they still deal normal damage? or power attack damage?
Obviously though it seems bad that I'd have power attacks taking same stamina costs as normal attacks..

You need to have a look at it...all the attacks have their own stamina mults and damage mults that you can change. Flagging them only "activates" them as draining stamina, which you can set to whataver mult you want. The mults are just that, multiples of the base values. The stamina mult is the multiple of the default powerattack stamina drain (also affected by weapon weight).

The only workaround i have for bows atm is to completely eliminate stamina regen while the bow is drawn. I reduced stam regen by 50% when blocking or sneaking. This way, in addition to blocking hits costing stamina, you are penalized for blocking longer than necessary. If you are overly defensive, you won't have the stamina to be counteroffensive. Sneaking was just to nerf cheese stab and hide tactics at high sneak levels a bit. These were done via spells/perks with conditions and work flawlessly. I thought the stamina regen penalty would be laggy but it kicks in (and out) within about a half of a second.

Are we by chance, attempting to make a very simlar type of combat mod?

For example, are you attempting to make shields actually stop damage, instead of taking away health?

Interesting, I didn't have to do any of that scripting to make sure you couldn't attack without any stamina.
Becuase, once its flagged as a power attack, if you don't have the stamina (or any stamina rather) you can't attack. Which is exactly what I wanted...

Now I just have to tweak the values better. Some reason, Its draining 100% of my stamina. (350 in my main gameplay base power attack = 15 stamina, with 2x multipliers normal attacks at 15. so somewhere I've got it messed up.

Nope. I started off doing that but didn't like the results because it makes block skill advancement redundant. I instead changed a lot of other GMSTs for blocking like recoiling and staggering. I didn't like how you can repeatedly beat on someone who is blocking. Yes, it is more "realistic" to allow that but I'm more concerned with gameplay balance. Whacking away constantly at a defensive NPC until he's dead is cheesy and far too easily done in vanilla. I did tweak the max block to go up to 95%, but i left the min values relatively low. The idea was to make it so if you attack someone blocking (especially with a shield) your attack will be staggered, not the person blocking, but if you are unskilled you won't block as much damage. Not perfect, but it's working out for me so far.

If there were a way to do it, I could tie in stamina-drain on block with the skiill, so it wouldn't make the block skill redundent.
Besides, theres other parts in the skill tree, that makes it not-so-redundent.

I just find the idea of someone blocking, and taking health damage laughable. (I think it shoudl take stamina damage)
And it shoudl be possible to pound on the shield until they can't defend anymore. (Or better yet, useing a
power attack to break through a shield, or to stagger the opponent.)

I'd love to tie in damage output to correlate with the amount of stamina you are deducted for blocking.
A simple 3:1 (3 damage : 1 stamina) ratio would suffice. a 50 damage weapon, would deal 16 stamina damage. a 250 damage waepon, would deal 83 stamina damage (easilly obtainable)

Well, I believe the system is already in place that deducts more stamina from higher damage attacks, should be in the GMSTs.

fStaminaBlockBase - Base amount of stamina deducted
fStaminaBlockDmgMult - Amount deducted based on attack damage

Kinda funny you want to go with 3:1, since my fStaminaBlockDmgMult is set at 0.30...very close to that.

A couple of things I'm not sure of here though. I haven't tested if that is based on the raw damage, or after the amount blocked comes into play...hopefully it is raw damage. This way you can put the damage blocked to the ceiling and still take stamina damage from attacks. I'd play around with it, I myself just got lucky and found the variables i wanted so I haven't messed around with it much.

If I were to guess, there are some elements we are going for that are very similar but the overall flow of combat desired is likely quite different. I'm more of a fan of traditional RPGs so I have tried to make combat lengthy, tactical and more character skill based than player skill based. Movement speed in combat(weapon ready/bow ready/magic ready) is fairly slow and movement while attacking/having bow drawn or casting is even slower, but the attack speed is still fast. You either block it, bash it or get lucky and avoid it occasionally if in light enough armor. This way, character armor skill and block skill plays a more significant factor and it also increases the significance of buff or debuff spells. The idea is to find the balance of feeling in control of my character's survival skills vs. my character's skills attributing to his/her survival. I personally found the prior far outweighed the latter in vanilla Skyrim. I want there to be some fights I absolutely cannot, will not, ever win without significant advancement merely because my character's skill is too low compared to the opponent, similar to turn-based RPGs. Of course this is already true to some degree in vanilla, just not as much as I want it to be. It's the one thing seems to be the bane of action based RPGs to this day, for me at least.

Ah, Mine is pretty much based on my impressions from the game Dark/Demons Souls. I really wish they would have put that games combat system into Skyrim. (I might have even bought the console version if they had...)

Basically its a hyper player skill game. Not so much based upon hand-eye-cordination, but on memorization, and knowing when to block, when to attack, how to attack/how to dodge/block, and above all else. Being conservaitve in your actions.

To put it simply. I had a boss fight, I had 25% stamina.
I had a choice.
Back off, regen some stamina, and keep my shield up, so even if the boss did hit me, I wouldn't die.
Or, I could hit it once, and finsih the boss off. But if I missed? If I failed that attack some how?
I'm Dead. Dead Dead Dead.
I gambled. I missed the boss.
I cursed, and was waiting to die. only the boss decided not to attack the way I had expected him to.
Any other time? He woulud have snapped my back in twain.

To me, the combat should have ebs and flows. Not so much the person with the most possible damage output wins, or any of that. But the smartest player/npc wins.
Its really alot like gambling... Do I put that coin in and win big? Or do I lose it all?
DO I block that attack, and possibly get staggered becuase its a power attack?
Do I dodge? (what if I screw the dodge up, and get hit anwyays? without my shield out? totally exposed?)
Should I try to attack before i'm attacked? if I miss? or the enemy dodges and counters? or worse yet, Riposte's me?

The idea for me, of having shields block all the damage, is to give those with the biggest weapons, or the most weapons (dual wield/great sword/axes..) something to give them trouble how do they deal with a defensive character? attack,get wore out, then get stabbed in the face with the shield-guys sword.
Or, they could test the s hield-wearer, wait for them to attack, dodge, and stab them in the back.
that kind of thing.

Obviously I can't emulate that combat system perfectly in Skyrim... far to many variables.. But making combat faster to me, seems to make it more action-orientated, and less turn-stat based RPG. (doesn't mean that dark/demons souls game isn't stat heavy, stats make you have more health/stamina/magic, deal more dmg, ect. The numbers are small enough, that even the earliest level 1 monsters, barely hurt you, but they can kill you if you aren't paying attention. the big mobs, can still 1 shot you, but you can deal significantly more damage to them. More damage = Less time in combat = less chance of being slaughtered.

I'll probably have to tweak my damage down another 10 or 15% from its current values. And a bunch of playtesting just to make sure the player doesn't get slaughtered to easilly or doesn't slaughter everything to fast. Getting that first strike is... very important, but I also don't want combat to become fast, and meaningless, without threat. I want you to kill the same level enemy, with just as much ease, as they have against you. Combat lasting 15-20s max. Afterall, real combat? First blood was ussually the winner.

Many good points but again, I am a svcker for gameplay balance over realism.

All enemies in my Skyrim regen health. Sound unrealistic..and annoying?

Probably, but balanced when the player has this boon. It means you gotta take chances to win. Damage output is fairly high, higher than default skyrim, but if you back off or run away you are going to pay for it. It makes certain AI fleeing routines make more sense. When wolves get low on health they flee for a bit..why would they give the player a chance to recouperate but come back to fight just as injured as when they fled? It means you need to tactically decide which threat you need to deal with first instead of running around like a homicidal-maniac-chimp from target to target avoiding blows until everything around you is dead. It means you can't just blow your entire magicka pool as a mage and regen mana while running around like a homicidal-mania..you get the idea.

The stamina use for weapons and power attacks is also fairly heavy handed(bad pun). It's actually a risk to use power attacks..no more of this chaining off 3 power attacks in a row and 'fight over no consequence' crap. You use two in a row you are probably going to screw yourself unless you start chugging potions. But..stamina regens a bit faster so its not like you have to wait 20 seconds in between. I'm still getting used to this part, it's difficult to untrain this dependancy. Getting pretty close to this.

Similar on mine actually. Thats one of the reasons I loved darksouls, a power attack, not only did more damage. But it svcked up nearly all of your stamina, and, if you missed, it left you totally exposed. Taking something like 1.5s to recover,more than enough time for an enemy to come back and nail you.
Infact, every attack that misses, (except bows/crossbows) staggered you. which is fairly realistic. If you hit an opponents shield, your weapon would bounce off. Not quite a stagger, but it took longer to recover than a normal attack...

hmm..gives me an idea. I bet you could make a condition where if a power attack misses the attacker could have a stagger (spell) effect on them. Likely would be buggy and look quite silly in most situations (depending on how quickly it is applied) but I'm curious about it.

If you are considering doing this yourself, you would likely have to change some stagger animation conditions to see any results, I believe one of the vanilla conditions states that you cannot be staggered while powerattacking. I have this condition removed already myself without seeing any unwanted side effects. The end result of just removing this condition is actually quite interesting when you are staggered while powerattacking, you still complete the animation and the attack follows through, but the staggering effect totally throws off your aiming angle, so you often miss entirely.

Reading back to the first page, I noticed you stated you were able to increase magicka damage of spells without increasing cost by unchecking the autocalc, I might be wrong but I think this also nullifies the cost reduction based on caster skill in that school of magic.

Not sure on the cost reduction you mentioned, but even if it does, I think it might just balance it out from being to powerfull.
Main reason I increased magic, was... upper end melee weapons dealing around 150-200 damage, can just plain one shot alot of low level npcs. higher level, takes a few more hits. (dependent on armor/blocking/ect.. sneak almost gaurnteed 1shot.. which I like)
Magic should feel powerful. And should deal alot of dmg (IMO) it should feel powerful, like magic should. So i'd rather have a spell, take out an npc's hp by around 75% at level 1, then to take 10 shots to kill it. (Which is about what I had)
However, leaving auto-calc on. to get those levels of damage i'd like to see.. Made level 1 starter spells? Uncastable...

I had hoped to be able to change the formula its self, to increase damage to magicka ratio, keeping magicka the same (or increased by 10%) but increasing damage by like... 150-350% across the board.

most of the damage values I have are obviously going to be adjusted. I've already toned damage down abit, just to make combat at level 30, less 1-shotty.