[Koha] a librarian's question

Hello! We recently joined the mailing list and read numerous emails with very technical questions, of which 10% I can understand. My questions: 1. - Being in Acquisitions, wanting to delete a whole record, lets say that title is being withdrawn, how do I do it? Can I use that "barcode" number again, (in our case it is up to WNTS3986) or will it automatically continue the sequence when I enter the details of another book? 2.- How do you differentiate between a 2nd copy and a 2nd volume, and where? By now you have guessed we do not use MARC records, and we are not online, it is a small special library of about 7000 vol. Thanks, Silvia Soto-Bussard Librarian Theosophical Society of New Zealand, Wellington Branch.