The ONLY thing that this mod ever did was to not display posts from the indicated board in the "recent posts" list. It does not stop the posts from being marked as new, it does not stop the posts from showing up in your RSS feed or in your "topics you have posted in with recent replies" list.
So, your item #4, which works, is the only thing this mod was ever intended to do.
Other functions would take more involved code, spread across multiple files, since other functions are handled in other files
