I can see this mod being essential when teh modding community is more established, well done guys!
I really want to play the remainder of my game hearing that dragon cry and going "oh sh*t" looking up and at the same tiem gonig to stealth mode. I want to have encounters where I only want to fight them near a town where I have lots of guards to help me!
Some advice I would love to give...
1. keep the focus of your mod on dragons; dont tweak other aspects of the game such as items and crafting; instead of making these other things optional plug-ins to your mod, have them a separate mod altogether. Not only will this make the mod less daunting to players to download ("do I really want all that, or jsut the making dragons ahrd bit?"), but it will help maintain a Mod Identity, image and give it a strong "brand".
2. As you may have read on the general forums, some people dislike how some NPCS's such as merchants die to normal dragon attacks, your mod will compound this issue by making them that more kick ass. It would be nice if you improved non-combat NPC AI to run and hide in the nearest building until the dragon dies and they all run out to watch you melt his skin!
3. In a certain quest the player can encounter an undead skeletal dragon, having these spawn in the outside world would be amazing, just walking around pwning the country; and if you can make them fly, even better! - few nice particle effects, blue or green would give them a very magical feel!
Keep up the good work guys: Dragons are the core pillar this game is founded on, and you are making that pillar stronger!
NPC's dying isn't something that can be realistically addressed without the Creation Kit at this point. There was a skeletal dragon at one point, and a significant number of users complained about it. Lastly, the mod is "focused" on dragons. Dragons & dragon related content. The optional plugins are there for a reason. Use them, or don't. The creatures option is 3jious own little side-project.
those are your opinions. and considering that one of you is the mod author, that probably makes it final. I, however, disagree on all the points.
not just a healing spell, any spell. Conjuration would be a lot of fun, even if weak. besides, alteration spells could be used against other npcs since dragons are the most impopular creatures of skyrim wildlife, for immersion.
Summon Dremora Lord?

but honestly, I don't know, I tend to play low-level for more challenge so I have not met the most powerful enemies

Let me try again here.. .. Healing spells just lengthen dragon fights further, something that is already achieved by the increased health pool. Self-healing enemies are never much fun to fight against. Not when it's a dragon that can actually kill you. Bandits with potions are one thing.. A dragon is another. Dragons don't need restoration spells to kill undead either, they have claws/teeth/shouts for that.
Alteration & Illusion spells are tools for the player to use.. They just do not work in the hands of an A.I. NPC. Besides a temporary invisibility spell perhaps.
3jiou has made better "Destruction" type spells than what is currently available to the player.
I already mentioned summoned creatures as somewhat useful. Specifically the Dremora lord...
If you feel you can explain your position better, I'm all ears and willing to listen. If your only example is something I specifically mentioned though, I rest my case.