Questions about the library app

When designing the user flow #8 we came into a few questions about parts of the app that we were unsure about, I just wanted to put them all in one place so that we can all share our ideas on them.

1. Can there be more than one copy of a book in the library?
2. How many books can a user have on loan at once?
3. What is the flow for requesting a book be added to the library? Can the user just request, or do they have to answer questions? If they have to answer questions, what are those questions?
4. What is the flow for checking out a book? Do we warn the user to only check out the book on the app when they have already physically got the book in their hands?
5. What can an admin do that a normal user can't?