Get some camber plates mate.
As for the drives, get the ones from 328 or 330. My ones were ok even after many hours of abuse. Once I've used soft front racing tyres on the rear axel, destroyed my diff but drives were fine.
You'll defo need higher diff ratio. Now your ratio is 3.07, I had same ratio in my 330i and it was too low.
Don't mind mapping this engine, it's pointless. Just cut the cats out and replace your intake manifold with the one from 330 or 325 (m54 engines only). Cheap power there
http://forum.e46fanatics.com/showthread.php?t=691568