what kind of amp do i need? 3 way? 4 way? 5? how do you decide? the size of the sub? or the type of head unit?

 

All of those questions are up to your tastes. Give us a little better of an idea of what you are looking to accomplish.

 

well im planning on putting INFINITY KAPPA 63.5I 6-1/2 in the front and the back (these are good speakers i assume?) i am putting in this cd player:

http://www.crutchfield.com/S-SHT3L2l...p?i=113KDCX569

and i am probably getting 2 10 in subs. i dont know what kind..i listen to rock and its usually turned up.