1. Some of the elevators (most notably the one to enter the dealer's room) do require an accessibility flag to use, so yes, your friend will need to see the member accessibility booth by registration to get one. If you go with your friend, and will be helping them at certain points, you can request a companion flag to be with them, which will allow you to join them in the elevator among other things.
2. I do know there are plans to accept at least one app, unfortunately, I do not remember which it was, so I will leave this for someone with that info.
3. As of right now, a mask will b