Oh, of course he can take them! It's a library, silly, so long as he returns them. He has to return them. Don't keep them, Quentin, or you won't like what happens next. :)

Also, alas, no, there are no books on the Librarian themselves. Although they do find him a book entitled The History of Libraries, 600 BC - 0 AD (Volume One), so that's . . . something?