Upload files still exist even when we delete all posts using it, and wasting disk space if there's too many files.I think a command line API should be given at least.
There is a report that shows abandoned files. You can delete them manually. A bit of a pain, but there is little other way to be sure that something isn't needed.
Limiting posts to people with certain badges is one thing, but groups and their permissions is definitely something that needs to be flushed out a bit more in the future.