Question
#11 Yes, the distance between the tire and body. This separation presses the tire to the track. To much and too quick can overwhelm the tires ability to hook.
#2 Ok
#3 It is possible in some instances with leaf springs to still top out. The rear of the leaf bends, especially unclamped and can actually have greater travel than hanging static.
#4 Dropping the front of the spring will raise the car some. But it will reduce the tendency to separate because the instant center is lower.
#5 Being maxed out on rebound will not allow you to slow the separation any further without revalving. The fact that the compression is full tight may be contributing to the bounce after the initial hit. If its to stiff the tire cant come back into the body, thus it bounces.
#6 Stay here for the time being Get the back taken care of readdress the front after.

I think taking out some separation and loosening the rear compression would be a good 1st step.
Doug