but specifically what are the other dvd's for?
The cds and dvds contains the same pacakges (some computers don't have dvd drives).
All the Debian packages are crammed into these iso images.
and where is a list of the repositories on each
What do you mean? Are you asking for a list of packages in each iso file? ...if so why?
Or are you looking for a list of Debian pacakges? If so you can start at: