Ignition switch & noise from under the car

I have a 2001 honda civic, 4AT, 2 drs DX. Whenever I drive the car one can feel (and hear) a noise like something knocking under the car and also one can feel a very faint vibration in the steering wheel while driving. Now I don't known if it has something to do with the fact that recent 3 of the 4 engine mounts were replaced and regarding the ignition switch sometimes, after turning the engine off the car key sticks in the switch and one has to turn the key on and move the shift lever from Park to Reverse and back for the key to come out