I get to the point that Wheel and caliper was removed. I tried to smash the rotor off with he rubber hammer, but with no luck.
There are two bolt holes in the rotor... I think they are M6 x 1.25, you can usually find a spare couple of bolts somewhere under the hood. Insert the bolts into the holes and tighten them evenly into the holes. The rotor will pop off easily after a few turns no matter how rusted it is...
What kinda C-clamp do I need to push the piston back?
I haven't done Ls430 rear brakes in a while but if memory serves, the pistons don't push back in... they turn in, you need a special tool, $29 at Harbor Freight, a bit more at an auto parts store..