The last pics are of blocks sanding irregular shapes. I have not seen the small belts, but I am guessing they may fit over the rubber items? My wife had a Porter Cable sanding tool that had a ton of the rubber shapes for sanding just about anything, but as I recall you had to cut your own sandpaper to fit. Memory could be a little off on the sandpaper cutting part though, it may have had sandpaper to fit the sanding blocks? It's been a while...
I would say your guesses are pretty close on the other items, but I am not sure what they really are or what tools/holders etc. they go to?