Re: AWD controller, i'd put that near the top of the list, powerdown out of corners is hopeless in R32s....as you must already know. I just got the austalian ebay one for $160 which helps massively, but all the serious guys say get the Ruzic...
Re: Brakes, dont worry about changing the rears, and for the fronts many have had success with the G4/D2 chinese stuff, which accept AP pads. Used to be around $2K for the kit which includes rotors, calipers, adapters, braided lines and street pads. I got EBC yellows for my G4s for just over $300. There's been a couple of good threads in Suspension/Braking/Tyres about them, so search there.