Definitely more like Gateways, and I think it's not so much we're interfering, as setting right things that go wrong, or just surviving. Like...most recently we all were asked to go help retrieve Cupid's arrows that had been stolen, and the thief was causing mayhem in Ancient Greece.

Before that, another person here and myself were pulled IN to one of the books. Honestly not sure why, just...we were. We had to learn about that world, so we could effectively find our way out again.

For the other questions, I'd talk to one of the Librarians or assistants. My impression has been we're here to help keep them safe from each other, and outside threats.