My question is on the
<dc:identifier>. Is the
<dc:indentifier> unique and hashed to an IP address or MAC address?
As long as the identifier is unique, it should be fine. At the above link, the IDPF says:
Yes it should be unique, and no, it is not hased to an IP or MAC address.
There is however, no necessity that this is a UUID. The only premise is that
E.g. the epub 3 examples mostly use a URN, and AFAIK none of those use an ISBN.