I doubt we'll get FM+ ever. But I do hope for some voice acting in 358/2 days. At the very least, the opening and ending scenes, and a few other scenes throughout the game.
I would guess sometime around holiday 2008, or maybe early 2009 depending on how development goes.
I don't see any reason to think there will be none. Most of the game is set in Twilight Town, so it'd make sense to at least see the FF characters who were there in KH2, even if it was just as cameos. And when they do travel off world, we could see a few other cameos. I doubt they'll play any real role, but FF cameos are kind of a tradition in the series.
This isn't really known yet. There's such a small amount of info known about this game, so for all we know there will be more keyblades/dual wielding.
