I need more time to think to really consider these questions, but I just want to add that your number one is my main concern as well. YKW knows how to track his supporters down, and I do think the dark mark is part of it. It's why so many of his turncoats were freaked out when he returned. They may not be loyal enough to her to rescue her, but they may be angry enough if they believe she's deserted to track her down.
Question to older Order members: have we ever done this before?