1. I THINK this is your throwout bearing. Someone else can probably confirm.

question 2 - i think you're idle should be more like 750-800. Make sure your throttle return spring on the carb is strong enough to be pulling the throttle plate all the way down to the idle screw every time. But not too hard so you're ankle gets a workout. Unsteady idle can be caused by a lot of things though. try googling for unsteady idle or surging idle.

3. This is not surprisign given the miles. I have the same thing occasionally. I think its caused by dirt and mud piled up in old leaf spring bushings. Fix the problem short term by power washing out the mud and applying some lubrican to the bushings. Fix it right by replacing the bushings.