Regarding the steering wheel sensor. I had this problem too after i made my changes to suspension and drivetrain. First my local shop solved this for me by hooking up the GT1 and calibrating it . They did this for a small fee , and it really is very simple. Later on i changed some stuff on the drivetrain by myself and got all the warning lights again. This time i calibrated it myself by turning the wheel lock to lock 5 times. Worked perfectly and never seen the warning lights again.
I also have the Bilstein suspension , PSS10's i have. My fronts will be replaced soon , Bilstein send my shop a new set and apparently they should be a revised model that should not "clunk" annymore
My front is very low too at maximum setting, but in the rear i have absolutely no height problems. I do have all the M3 parts in the rear with the Bilstein pss10 m3 shocks. But i have alot of room for height adjustment.