You will be able to develop both characters as you wish (as with previous Divinity games, there is no strict class system). Not a lot about the equipment system has been revealed, but there should be a variety of armour (possibly robes, etc, if forum requests made after DD were taken to heart).
Thanks, Raze

I hope one can be a mage or archer without wearing pieces of platemail armour.
With respect to turn-based, the number of times you get into combat will be much less compared to the previous Divinity games.
Again, great news! A few challenging fights are much better than lots of effortlessly won fights.
You can also waste an appalling amount of time on encounters that your group can swat in one hit while the game changes to 'battlefield' then you wait your turn, etc. You could have looted the body and been a hundred yards away in real time with pausing (By far the best system).
I agree that turn-based combat should not be used when you are able to defeat opponents with just one hit. A hack 'n' slash game with turn-based combat would not be a great idea. But it looks like Larian will focus on fewer, more challenging fights, which I appreciate. And that's where turn-based combat can really shine.
I'm with Alrik on Steam, BTW. If the game DEMANDS Steam in order for me to play offline single player, it is a no-buy from me. It is a particularly pernicious form of DRM that I will have no truck with.
If Steam is OPTIONAL and only required for multi-player, I have no problem with it.
Same here. If a Steam account is required for playing the game, I will probably not buy it, despite its promising features.
The RPGWatch preview only mentioned Steamworks, though, and that's not quite same.
Concerning the co-op dialogue system:
I actually don’t understand why nobody did this before – the moment you start thinking about making a real RPG with cooperative multiplayer in there, you can’t but end up with something like this.
I guess this hasn't been done yet because it looks like a lot of additional work. If there's an additional line for everything one of the lead characters can be saying, that's at least twice as much PC dialogue, and possibly even more dialogue if you allow NPCs to react on disagreements between the lead characters. It does sound like it could have a lot of potential, though if it basically comes down to the lead characters having to agree on one option, I wouldn't need an in-game system for that. When playing co-op, I will use voice chat anyway, and it's easy enough to agree on which dialogue option we will choose via chat. So I hope at least some NPCs will react in a specific way when the lead characters disagree. This would require even more dialogue and could quickly become very costly if all of the dialogue is done by voice-actors.
While we're at it: On the website, you can switch to different languages. Does this mean the game will be fully localized?