I have a 1991 300SEL w/ 165000 miles. I really want to keep this car forever. I am trying to repair what I can now, and hopefully tear everything down in a couple of years. I have a few problems that I need help with. I am amateur mechanic and am trying to do as much as I can to save $$$.

Problem 1
Squeak in steering wheel
happens when turning left or when steering wheel is returning left to neutral position after turning right. It is not the power steering pump and it it is a short high-pitched squeak that sounds like it is coming from inside the cabin.

Problem 2
I just noticed this the other day when I had two normal weight adults in the back seat. The back end rides a little low and scrapes the road even on tiny bumps at low speed. Do I need to replace the coil springs??

Thanks in advance for your help.