Nope, that's why UE3 is used. It makes it possible, because it has a higher processing capability than MT F. You have 30FPS, that's sure, but for this you have less loading time (if any at all), while maintaining fluidity and complex action (moving backgrounds, enemy AI etc).
The Stances are an improvement over the Styles , because they simplify the system. You don't have to switch between 4 different ones, therefore freeing the digi-pad, which was a hassle to use anyways. As I said: You can count the moves, you will find a lot of moves, that were style-moves before implemented in the angelic or demonic Stance (Glide, Shredder, Rainstorm (human stance) etc), you just have to look out for them in the trailers so far.
And about the Limbo-thing: It turns DmC into more than simply "Kill enemies until the way is cleared, obtain that object, backtrack and use it at the beginning of that level again". Platforming seems fun so far and more intricate (if only visually) than the grappling scenes with Nero for example).
Sure, but then again, why would I buy GOW3 if I already played GOW 1+2? Also, I didn't really get that from your sentence above, at all.
DmC is not DMC though. GOW is a game with story. From GOW 1, 2, 3 etc til story ends. DMC story is not same as DmC. DmC is a new and rebooted game that only uses the ideas from DMC.