Looks very nice and compact. I could replace the buffing grinder, belt-sander/disk sander with just this one piece and have it take less space than my belt sander alone. It also looks to be well made.

About slowing down the motor it may be possible but you'll need at least a 6 Amp rheostat. It may even work with an electronic dimmer but may blow it depending on the dimmer's circuitry.

I have a scroll saw with a 1/2 HP motor and it has a variable speed control, although for a grinder they may have used a constant speed motor that cannot be speed controlled with a rheostat or electronic dimmers.