Headlight Switch removal
The removal of the switch itself is quite easy (or should be). The cluster also should NOT have to be removed. As you stated..the knob itself has pulled off the bar which runs into the switch itself. To remove the light switch you first must pull the electrical connector attached to it off. Reach up under your dash (trying to look) and pull the connecter off. Next, just un-screw the locking tab where the knob itself went into the switch at the front of your cluster. You may have to use needle nose pliers to turn the locking piece. The switch should just fall out of the cluster face. ***Note when out*** that the switch itself has a little push pin on the side of the switch. This push pin allows you to pull the whole knob/bar from the switch without pulling the knob off. Replacing the switch may fix your amp problems?? I'm not to sure about the reverse indication light...Only that a bulb has to be replaced on the backside of the cluster itself...(could be a *****, however you maybe able to feel the rear of the bulb and turn it about 45 degrees to get it out.
Good Luck.