Regarding the rear suspension noise, your car has ride leveling, there are a few things that could cause the suspension to bottom out:
1) The ride leveling valve is bad
2) The hydrallic pump is bad
3) The accumulators are bad. Should be changed every 60K miles
4) The shocks are bad
5) The level is set too low at the leveling valve. Easy to reset.
The first thing that I would check is leak. If nothing is leaking and the accumulators are new then it is probably a simple ride height adjustment. Good luck.