1)
My companion can hardly carry anything. The more we proceed into the game and get level up,
the less she seem to be able to carry. Yes, i usually upgrade her gear, and she is now in full Steel
(the better kind) with a mace, shield and bow.

Will it make your companion better by upgrading their armor?. And if so, i should probably enchant
all her gear with "carry more" enchants.

2)
Whenever i fight some kind of leader for a thief gang in a fort or cave and toss the Soul-drain
spell on them before i kill them, i get the message "You don't have a big enough Gem" even though
i carry several Grand and Greater empty gems.

Why is this?. Just now, i went into a fort and killed a leader while he was carrying the Soul-steal curse
(they are blue'ish) and i didn't receive any soul upon his death.

3)
Currently i have the "become werewolf" quest started and i am suppose to go into the cave and
drink the blood. My question is: Will this affect my char in any way which i cannot undo and does
it have negative impacts (will i have to start eating people to survive) ?.

4)
Why does people keep telling me i look sick?. My char is an Orc, but im beginning to believe i
actually AM sick. However, i watch the "status" and no illness appears.

5)
Why does an Elven regular 2Handed sword have more damage then my exquisite 2Handed Orc sword?.
(If the lore is correct, an Orc weapon should do more damage, but elves weigh less)....

1. No idea. Sounds like the new gear you've given them weighs more and therefore they can carry less. But I'm just guessing.
2. You can't soul trap people? I think you'd need a black soul gem.
3. You gain 100% disease resistance, but lose the ability to be rested. You can end the curse at the end of the companion line... or... not.
4. You probably are sick. Check your active effects, or just quaff a cure disease potion to be safe.
5. Skill? Yeah, that is dumb.

You have to have black soul gems for human souls. No negative impact to becoming a werewolf. The positive is that you will be immune from disease and at lower levels, it is a benefit to turn into a wolf, at higher levels not so much. You can at the end of the guild quests cure yourself of the disease. Look in the magic menu at the bottom forgot what it was, maybe active effects and see if you have anything in red. If you do, you have a disease which you need a potion of cure disease for. Companion carryweight. I don't bother. I just used a console command to increase my carry weight. Got sick of them telling me that they are sworn to carry my burdens, lol.

1. Your companion doesnt level with you, so her stamina isnt increasing.
2. to soul-trap 'human' souls you need a black soul gem
3. you can cure yourself later on in the quest, its not a big deal. being a werewolf doesnt affect you like being a vampire. if you want to continue the companions quest you have to drink the blood.
4. Try going to a shrine, or using a potion. usually when youre getting comments like that you are sick.
5. no idea, sorry.

1.) Quoted from UESP: "Followers do not actually have a carry limit and are not affected by weight encumbrance (though still appear to be affected by armor encumbrance). The limit that occurs during trading is only a limitation in the trading HUD. If you command them to pick up items off the ground they can carry an infinite amount of items." Loading up your follower with heavy armor will cause them to be slower than you if you are wearing light or no armor.

2.) You need black soul gems to capture the souls of people.

3.) It can be undone if you do not wish to keep it and there aren't really any negatives I ever ran into as long as you don't transform in front of anyone.

4.) Are those people alchemists? I know the alchemist in Whiterun will say that to you no matter what race you are.

5.) It's just how the weapon ladder goes.

I have a Black soul-gem i got from a female boss in some dungeon, a real [censored] i might add...

I tried using it once and it vanished, but i have heard of a Gems that doesn't vanish.
Aren't there a "light" and Black gem that is re-usable ?.

. Normal black soul gems are one time use, just like white ones.

Visit Azura's shrine and you will start a quest to recover Azura's star, which is the only reusable soul gem. Every other soul gem is one use only and breaks after using it. During the quest you have a choice to return the Star to one of two people. One of them restores it to normal, allowing you to trap "white" souls (animals and undead only) and the other will change it to The Black Star, which traps "black" (men, mer and beast races) only. The Black Star is a better choice, since every black soul is a grand soul.

followers will get duplicates of their default weapons (usually bows) each time you recruit and and ditch them.

the the vast majority of them will also not level unless you disable then enable them.