Hi there, thanks for providing a detailed overview of the issue, there’s a lot to unpack so lets begin by clearing up the initially confusion in differentiating Data and Asset storage.
Please check this guide for in detail explanation how Data and Asset storage is handled.
Then there is this guide that will help you clear your Data storage of any excess files or modules, as I suspect that modules might’ve gotten stuck in there during installation or updates, so check all the tabs while viewing Data storage for any .zip files as well.
And to answer your 5 questions, in short answer to all of them is No, with caveats as unexpected issues can always happen, in which case we’ll ask permission to access your account ourselves for detailed review.
So please go through those two linked documents and if it still looks like the numbers don’t add up please do share screenshots of your Data storage and we’ll see what’s happening from there.