One question bugged me for a while now: what's a "top level comment" and is it some kind of a privilege to make one? Is it the article itself, or a comment that's not a reply to a comment? (Since no one got mad at me yet, I either haven't made one, or nobody noticed).

It is what you get when you click the "Add new article" button at the top right and well, yeah, it is an article itself. The privilege you need to post one is about 50 karma. Maybe 30. (Or, technically, be an SIAI donor and ask someone. But that happened only once and he was downvoted to oblivion.)

Make a post if you think you have something significant to say. This is the discussion section, not the main page so the standards aren't particularly high.