It is the same PIN as your library account. If you don't one you can create one here:
You can choose a checkout period of 7days, 14 days, or 21 days, with no renewals.
No, but if it is available to check out, check it out again. If there is a holds list, place a hold after your loan expires.
eBooks will automatically expire at the end of the check out period. No late fees! However, if you finish early you can return the book from your bookshelf.