bondage - When Bischoff got slammed, he landed on a table... of sorts. What they tryed to hide was the fact that the table was supported by a large black cushion. So the table was most likely weakened to shatter on impact, and bischoff was padded by the black thing. Whenever someone gets tossed off the side of the ramp, they usually land on the pad, or the piles of coils, that are most likely some more sponge or rubber.
I over analyze.
Prophacy - I don't think it is all forms of the piledriver. I mean, look at how many people take a DDT on their heads (RVD and Val Venis come to mind). I think it is mainly the sitdown piledriver. The tombstone 'should' be okay, because most of the impact in on the persons shoulders, which are landing on the other guys quad's.
I also think that Undertaker stopped using the Tombstone as his finisher because of his new direction of his character. He wants to get away from the Dead Guy gimmick, and the Tombstone is really a dead (har har har) giveaway that he is still the burial man. Let Kane do it for now.
And stop it with the stupid Chokeslams!!!!