Headlight Switch removal

On my 72 Duster, the headlight switch has finally met its maker. The knob attached to the bar has came completely out of the switch. When this happened I noticed that the ampmeter needle started dancing so there is something evil going on behind the dash inside of the switch.

I realize the switch has to be replaced but I am interested in finding out how this is best done and the easiest way. Does the entire gauge section have to be removed and if so, how is this done? If not, can someone detail how I can accomplish the replacement.

Also, my car is a 4-speed, how does the dash mounted reverse indicator light come apart to change the bulb. Mine seems fused together but I know it has to come apart some way. Thanks.