which amp to use??

[suitably_random]

ive got 4 way 360w 6x9's in the rear shelf of my cinq and 4" 45w speakers in the front on a 4x 50w head unit. what would be the best amp to use (i also intend to get a sub on the same one at a later date) and how much power would it draw? would i need an upgraded battery, or another one to stop it going flat on me all the time?!?!

Also, any hints on sound systems in cinquecentos would be great!

thanks!!