I always use emery cloth on my sander. It last a lot longer than sand paper. My sander came with a tool thingy with spikes on it. You put the new sanpaper/emery on the sander and push the spiky tool onto it. This puts the holes in it so when you attach the vacuum cleaner it collects some of the dust.
Belt sander works well on plaster for tarting up poor repair bodges.
If you are getting the impression that I am naff at plastering then you are right
