Airship - in answer to Q3, I think the only option would have been an abort launch command which would have brought the shuttle down on an emergency strip. That decision would have to have been taken early, perhaps within seconds of seeing the bit fall off, with very little data instantly to hand and would have taken a (!)VERY BRAVE PERSON(!) to make it.
Imagine facing the NASA bosses that afternoon when the damage had been assessed as 'negligible' and YOU aborted the launch.
As it happens, it would appear to have not been negligible, and lives would probably have been saved, but ...................