On the matter of FF characters making it into KH, anyone else miffed that there are no pre-FF7 characters? I think that they should have taken the Cid from FF4, he was the best. The voice for this Cid would actually fit him, too. Plus, I would pay money to have Kefka in one of these games, he's by far the most badass villain in FF history. Screw Sephiroth. Plus, Palom and Porom seem made for Kingdom Hearts. And if Kain was in it… Well, we all know what he would do. Fight with you for maybe five minutes, become an enemy, come back, rinse and repeat.
Besides that I'd really like to see a Chrono Trigger character in KH. It'll never happen, but I can dream. I think Robo and Frog would fit like gloves - Frog has that "I'm cool, but not too cool to show you the ropes" deal going on, plus he wouldn't look too strange next to Donald and Goofy. And Robo is just quirky enough to work.
Vivi being in this game made me real happy - FF9 was the only next-gen Final Fantasy I liked (excluding FF7, which I never got a chance to play). Vivi was always my favorite character in that. However, it PISSED ME OFF MORE THAN DESCRIBABLE that they gave him a terrible voice, made him a pansy, and didn't let him Firaga Roxas's dumb ass.