Boko pretty much summed it up. Just try to have one healer who can restore alot of HP to everyone (Cure3-All) so when super nova goes down you can get yourself back up pretty quickly. Also Remedys might take too long so if a character's only big problem is confusion, that might take care of itself. Or it could spell disaster so it's up to you. Limits become what you should really utilize to the fullest but you probably already know that having played him. Remember don't be afraid to use up your elixers, x-potions, turbo ethers, and megalixers as you won't need them. Vincent might not be the best choice since his limit is uncontrollable (anyone know if this is to the end of battle or if it wears off?) and if you're also using Tifa you'll probably want vincent to Heal as Cloud should be your main damage-delaing character.

Unless you really want to beat the game now I would suggest going out and doing all the sidequests (don't gotta go as far as KOTR) becaues it's really worth it. The game's got alot to do and to not would kinda be cheating yourself out of the whole experience.