Do not go to Wally World or Auto Zoo to buy one of their "refill kits." They are junk. And whatever you do, NEVER put anything called a sealer into the system. NOTHING but pure 134a (and PAG-46, if the FSM calls for it under your conditions).

Guessing the refrigerant level is a good way to harm your system, particularly the compressor. Using a proper gauge set and comparing to the charts in the FSM will get you close. But as I said before, you cannot ever be sure of the quantity of refrigerant without a recovery and refill by weight.

The steering wheel shake may be the front lower control arm bushings.

Can you replace the broken mount for the trim?