Hi just joined, great to have a KCC forum, I've got lots to share.
I found out about the forum from the KCC newsletter, but it doesn't look like the forum is linked from the main KCC website yet? Not on the front page or in the menus.
The website is probably getting updated right now, imho the forum links should be more prominent than the Facebook group links. Facebook is a terrible platform for organizing.
I suggest condensing a bit just so on a brand new forum things don't appear too unused/dead and instead encourage activity without being spread too thin. More categories could certainly be added in any time it appeared we could utilize some separation.
I've run big forums for several decades and in my experience this is a good approach, don't have too many sub-forums at the beginning. If the main/general discussion forum gets too busy, then look at splitting it up.
Buy & Sell can be a big draw, but it can also be a headache for moderators if deals go sideways.
KISS is good, get the basics nailed down and work on driving engagement.