2
Sounds like it is time to write some code...
My understanding of things is that once you enable comments (according to the systems prefernces) once you enable Anonymous (anyone can write...). That's the point of it. If you want people to be registered then theoretically you restrict functions such that there is a benefit to being logged in... like the ability to write comments, download files, etc.
If you want something different, I think you're pretty much on your own.
Ergo...maybe it's time to write some code.
