Rock and funk + death metal = Six Feet Under
Well if you have creative issues (can't agree on the music with the rest of the band) look for a band closer to your intention.
About the live performance thing: if you're comfortable rehearsing with the band, you'll be comfortable playing for a small audience, friends and family and stuff. Then it just gets bigger and bigger. You have to love what you do, though. You have to live to play music, otherwise you won't go very far.