Brakes are one of the easiest things to replace. There's tons of detailed DIYs. Just Google "E46 Brake DIY."
Rotors sizes are 325mm front and 300mm rear. (This is pre-determined by all online vendors as long as you're buying 330i brakes. All other non Ms have smaller rotors.)
Brembo blanks or Zimmerman are the equivalent of the OE rotors.
For pads I recommend Textar (OE), Pagid or Jurid (all essentially the same). Another option is Akebono Euro which are ceramic pads. They produce virtually no brake dust but at the cost of less initial bite. Your call.
Use ATE Super Blue for brake fluid.
Last edited by StraightSix; 12-21-2012 at 02:39 AM.