I just put 17 bookmarks in a file. 5 to a page. As I added the 6th one, the second page was formed, the 11th one added the 3rd page, etc. They are accessed by the page forward and page back button.
I don't know if there is a limit, anyone know?
I have a book or two with many hyperlinks, listing that each line item is hyperlinked, so I'm guessing there are no limits to those either.
My TOC is many pages so I doubt if there is a limit there either.