1) That sounds pretty nice. If it can be reasonably implemented.
2) I'm neutral on this. All it really does is make you have to stop doing what you're doing and repair something with a skill or go back into town. It might be an interesting challenge in a few select places when that can't be done easily, but it's usually just an annoying interruption.
3) Both of those sound like good ideas. I also liked how Beyond Divinity implemented stealth, where when you were sneaking, you could see the enemy detection radius. That would be pretty helpful it it were to make a return to stealth in Original Sin.
4) Well, obviously.
5) useful torches sound good and seem to be in line with what the game is doing.
6) Horses are only useful in a world that is too big for walking like Oblivion or Sacred or Far Cry. I doubt that Original Sin will have a world large enough that horses will be useful.
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Okay, my suggestions:
7) As I said before, I'd like conversations between the two main characters to have different portraits to convey different emotions. When you have a choice of what to say to your partner, and you mouse-over an option, your character's portrait changes to show the tone that you'd use in that selection. That would give you a good idea how the option would be received by the AI-controlled character, and it would let you do interesting things like having two identical lines with the same words, but said in different tones and producing different results, that would be neat.
8) I wouldn't mind seeing a return of the "Feign Death" skill. It could be even more helpful since there are cases where the party can split up and one person could get in over their head.
9) I would like some option or key on the PC version that would let you hide the HUD to take better screenshots.