most of these are open to the interpretation of the GM, although here are some thoughts about how i would or did handle it in my games:
- generally, players will not take the staircase if something as fun as a paternoster is at hand; but if they do, you can always introduce other obstacles or just let it lead them to similar challenges as if they'd taken the elevator. a door with a glass window, where they can see someone they need to help, comes to mind.
- i had the butler tell them which floor they should go on (they of course demanded to go all the way up, but he told them they had bsuiness to take care on floor <x> first) and it looped there forever until they got off. nobody thought about tricking this, but if they have clever ideas, let them and give them some new obstacles based on it.
- i had the administrator be less impressed by their actions if they used the butler's help a lot; and by extension offer them a worse deal when they got to him.
- i played the butler as a lackey to the administrator or maybe even an extension of the building itself (or a manifestation of the PCs fears, in one session). but i like your ideas as well, so i suggest to go with whatever feels fun to you and/or your group.
and i will investigate the difference between the english and german version, thanks for pointing it out!