Can I give my bookkeeper a month of the books?

Yes. The bookkeeper archive is one closed month as a single download: CSVs of invoices, credit notes, payments and refunds, a totals summary, and every document PDF exactly as it was issued. If the books move after you have taken one, you are warned, and you can issue a corrected archive that supersedes it. The original stays and is marked as replaced rather than removed, and there is a limit on how many corrections a single month can carry.