Some people say the hallways go on forever. I know one guy who lives in room 499, so they're all at least 500 rooms long. It goes on a while.

[That's the finicky thing about magic. It breaks rules.]

The residents will usually show up right before an event. I'm not sure if you could actually summon them in any way. Sometimes they'll show up for parties and stuff too, but honestly, I've never gotten a decent answer out of any of them.