Larian has released 3 screenshots from a test of the game engine (not the actual game), referred to simply as
Next Gen Game. There is some information in the announcements forum on stuff that they have licensed. Given the lack of public information I'd guess release would be on the order of a year or more away.
There is no 'best' combination of characters. I did well starting off with a warrior / warrior, then after entering the citadel in act 1 switching to a warrior / archer combination. Others have effectively used warrior / warrior or warrior / mage combinations. AFAIK 'thief' characters are generally part archer or mage (sneak, attack from hiding and retreat so your enemy can not find you, or just sneak in to get the first hit and fight it out). I don't know if anybody has tried a mage / mage, but I would think that would be difficult, both from a mana supply standpoint and the fact that AFAIK most spells do not auto-cast, so you would have to constantly control both characters, rather than setting one to aggressive the majority of the time.
