This seems to answer my first question -- a moderator or assistant CAN remove a post directly without any intervention by you. Correct?
If you do nothing, does it stay deleted, or does it pop back up automatically? Maybe if you're tinkering with the system, you should have a practice where if YOU don't confirm the delete within, say, 24 hours, the post returns to the thread. Of course, many people who regularly follow the thread will miss it since they will have read past that point before 24 hours are up.
It's not a perfect world, is it?