Thanks for your questions and your sharp eye. I'm working on a new draft, so I can immediately correct that mistake (and upgrade the explanation of the Night phase).
A full game of The Girls of the Genziana Hotel, in which you answer all three questions, takes about five sessions. You can probably get it in four if you power through, or it might take six if you really take your time role-playing. A one shot in which you answer only the first question is feasible in a tightly focused four hour session, especially if you lower the Complexity of that first Question by one.
On the Night Phase and the Dreams: you're on the right track, but play is a lot faster than you're imagining. Instead of an 'action' being a full scene with thematic unity, it's actually a smaller unit inside of a scene. While you, as the Mistress, can always decide to be a little more flexible, there are two basic moments for cutting to another girl or the next Dream prompt. These are:
- Narrative leading up to a move and rolling the dice.
- Narrating the result of a move and continueing the scene.
If you think this'll mean you cut and move the spotlight a lot, you're right, and that exactly how intense the Night should be. In terms of your first schema, it looks something like this:
- A answers the first Dream prompt.
- The Mistress frames a scene for B, and asks, what do you do? B starts to narrate what their girl does, up to triggering a Move.
- The Mistress cuts to C, frames the situation of their girl, and asks, what do you do? C begins to narrate the actions of their girl, up to triggering a Move.
- A answers the second Dream prompt.
- B rolls for their Move, and they and the Mistress narrate how the scene changes and the direction in which it will continue.
- C rolls for their Move ...
And so forth. Believe me, this will result in tense, cinematic play with eerie, threatening undertones.
After the last Dream prompt has been answered, you play one more series of "actions", likely the aftermath of some Moves. After that, the Night ends abruptly and you move onto the Dawn phase, exactly like you said.
With respect to answering the prompts, you've got it. If only one girl is awake, they answer. If there's two, they take turns answering. If there's three girls and they're all awake: A answers the first, B the second, C the third, A the fourth, and then, after the last round of actions, the Night ends.