Is the Movable platform that can go down to the water line and up to the top of the ship. It isn’t an elevator and you cannot ride it while it is moving When it is stationary it is a bar or Party space.
I know you think you have reservation’s booked but once you are on board you will find out that you don’t. On M and S class ships you can book reservations for dinner but the E class ships are all open seating
There is entry to the building, check-in for the cruise, and boarding the cruise. As soon as they open the building they will allow retreat guests to enter and check in. And once the authorities clear the ship they will allow them to board.
You may have misunderstood how it works. When you book on board, the booking goes directly to the Travel agent. Often it crosses his desk before I have even left the Future Cruise Office!
It’s interesting that not one single person has said they want lots more short itineraries. Everyone wants the longer ones. The ones that Celebrity has been taking away.