I'll defer to Dave and Eric, but I thought I'd throw in a few commnts:

Register as a street car: I'm not sure I would want to drive around a car without regular seatbelts and have cage bars so close to my unhelmeted head. You can certainly do it. I know a couple who do.

Brakes: As long as the pistons are the right size, new brackets and rotor hats are probably all you need to tranfer your brakes.

Suspension: The e36 m3 doesn't have a coilover system in the rear. It has the shocks and springs located separtely....thus you can't run coilovers there since you'll be changing the mounting locations.

Tires: "are 235/40/17 RA1s going to be enough?" -- define "enough." Sure it'll get you around the track. Is it going to be competetive? BWHAHAHAHAHAHAH!!! no.

Andrew Lee
'00 S4
'93 Civic: Honda Challenge #27
'05 Ram 2500/Pace Daytona

Brakeswap, where I get my brake pads and rotors

Some of my race videos