Personally, I wouldn't worry too much about #1, @Heather145. I sometimes get arrival times the night before, and you mention a code, so it should prevent you from having to wait around for her. If you have guests leaving in the morning, you will have to change your listing so that check-in time is defined rather than flexible. The name of her fellow traveller shouldn't be a hard one, though, so you could try firming up the message you send: "Hello again, X. I really need to know the name of your fellow traveller and your estimated arrival time. I'm afraid it is policy, and we cannot move forward until you do."
Will something like that work?
Often a failure to answer is just a "kids today" thing and not nefarious. To her, next week may seem ages away.
That said, do go with your instincts after giving her a bit more time. You can contact Airbnb with your concerns.