1) Sorry, this is completely your fault. You "thought" you had a tp but you didn't, I understand you not being happy but if anything that should be you're not happy with yourself. Cthulhu has been the same since almost 2 years ago when it comes to this mechanic, keep a TP outside of the lair!
2) Andariel and mephisto will have their own marks one day, no plans to make them drop existing ones.
3) No plans for anything like this as of now, world drop puzzles will stay world drop for now. I may change this in the future or add other ways to obtain puzzles, just not in the next patch.
4) Same as above.
3) This would make buying key of the old one completely useless, no plans to do this. Opening at the caches at the altar is just to make the caches not completely useless to those who have no intention of using Gold on a key.
6) Annihilus's were intended to be a little more work than before, because they were just way too common before. No plans to change this as this was the intentional outcome.