Re-activate Tire Pressure Sensor
#2
Ensure you have corrected the tire presure before reactivating. Once you have corrected this, go to the tire presure menu, it will ask you to reactive, hold "R" then confirm with "R". That should clear the error. Drive a few miles then check again to ensure you have the correct pressure.
#4
MBWorld Fanatic!
If it's older and you want to download a newer manual, sign up with your VIN, then find a VIN on autotrader for the later model and add that as a second car. It may say "doesn't match our records" the first time you add that car, but click on add again and it will take it. Just delete the car when you've downloaded the manual and only leave your real VIN as yours. That way you won't interfere with the real owner signing up some day. This trick enables you to get any manual you want.