I don't use a bench grinder for rust removal--just buffing with
a cotton wheel and grinding with a grinding wheel.
For rust removal, usually evaporust.
But if I'm doing something manually, sometimes steel wool. I
just picked up some abrasive balls for a drill at harbor freight,
so I may give those a try instead.
If I'm regraining something like a lockbar, I'll use a drill and
3M flap wheels with different grits.
For polishing, sometimes I'll use the bench grinder, sometimes
my drill with with a cotton buff bob, sometimes a variable speed
polisher for large surfaces with a cotton or fleece bonnet. For any
polishing, I'll use a tube of green compound. When done, I'll wipe
the part down with a microfiber towel.
But, it's an evolving process depending on what the part is, the
shape/size of the part, and the amount of rust removal or polishing