Regarding the CRJs tail strength - compare what happened here - the tail stayed on and the aircraft span - with what happened during the ground collision a few years ago between a Thai 747 and AF EMB-145 (IIRC) the 747 took similar damage to the AB here, but the entire EMB empannage was taken off! Either the CRJ tail is over designed or the EMB under designed? (Or the impacts were different, but that's a boring conclusion)