Diamond's annual revenues from comics, trade paperbacks, and magazines are estimated here. As for relating it to comics shops, that is much more difficult because the number of Diamond accounts is not made public. The number circulating for several years was 3,000 shops, but I would advise that even if you have a number, calculating averages from it is tricky. Some Diamond accounts are extremely large, encompassing mail-order operations; many others are game or hobby shops that dabble lightly in comics.
Most of the reader demographic research has been gathered by the publishers themselves, and is held internally. But you might be able to get media kits from them to see what they are telling their advertisers about their audiences. I would look around their publishing sites and see if there's any link to information for advertisers — however useful or accurate that might be.