How are you zipping up the book?
You have to do mumb-jumbo with the info-zip command-line tools (the spell is documented in various places on the web), or alternatively use special tools designed specifically to pack up an EPUB (heavily advised).
Otherwise you will certainly fail to do it properly.
The other error is, I believe, because an id cannot start with a number.
As you can tell, EpubCheck doesn't have good error messages.
Try FlightCrew, which is usually a lot more clear about your actual problem.