128i will probably be $25k-$28k and 135i will more than likely start out around $33k.

Wheelspin will be controlled through the brakes via ABS, much like Mercedes has been doing for a while. No 335i will ever come from the factory with an LSD; LSDs are reserved for M cars only, though hardly any possible way it WONT bolt up I'd say. Suspension is supposed to be based off of the E90...I doubt theres much difference underneath between the 135i, E90, and E92. Problem is the E46 M3 (01-06) differential costs somewhere like $5k-$6k IIRC, let alone labor. Supposedly there is an unlimited years/unlimited miles warranty on BMW installed parts, though I dont know if this would fly. It would depend on the dealership.