That is a big job without the right tools. There is not necessarily a simple way to get that without help from a 3rd party tool where you can get the list of reports, the total number of instances, size, etc.
Not really. If you know how to get this information from the BO system database then you can use either Query Builder or a BO report with a VBA-based data provider.
For the sake of being clear, the question was about using the CMC to drive out that information, thus my response.
While I don’t disagree with you, the Query Builder can’t aggregate the results as requested and the developer has to have SDK knowledge as suggested.
Check out this topic in BOB Downloads: https://bobj-board.org/t/118177. You may need to modify it a little to get what you want, but it should give you a start.