Jack --
I think this did it for me, man! You're the bomb!
I had some initial trouble because I ran the test and a segment failed due to the 'Allowed User' mod I had installed (which didn't work, anyhow). I uninstalled it using Boardmod, but then my board THOUGHT I had already installed the calendar mod -- I guess because I had ran the test.

This apparently had created some files in the "Packages" directory, which caused the mod to kick back errors when I tried to install it anyhow.
Taking a chance, I deleted the suspect files and VIOLA -- I think I've got what I need!!
Thanks for this... I REALLY appreciate it! I
STILL would like a "Hide Category" mod (but where everyone has access), but this will take care of some headaches for now. Hiding the category would still allow users to post details about their calendar entry without it showing up on the main board as a discussion topic.
Something to consider for down the road -- unless someone wants to make it for me! I'm not much of a php coder, so I don't think I could do it. But I would think a simple checkbox in the Create/Edit categories or boards section that prevents it from being displayed on the boardindex would do the job. That way you could even make categories or boards that come and go as you wish (like seasonal, etc.).