I am also curious about this.
I am worried about the stealth, specifically. It sounds like it doesn't really exist right now, according to previewers, and it doesn't really work at all when devs try to use it during the demos. I'm hoping the stealth programmer guys they are apparently hiring will be able to assist with this.
As to how to handle situations, ideally, virtually every situation should be able to be talked through. Not every situation, but many.
I'm also hoping that a "pacifist" playthrough, or one when you don't kill anybody (nonlethal takedowns only - apparently pacifism was mentioned as a viable way to get through the game in a preview or in that little brochure, I forget which), is possible.
I like to play many different characters, and I get sick of slaughtering everybody all the time in games. I always go non-lethal when possible, it's almost always more challenging and more rewarding.