Look into different blasting mediums. Coarse sand works pretty well on most surfaces, but not all. Some of the ones I use in my cabinet are, baking soda, crushed walnut sheels, plastic beads, Glass bbeads, fine, medium, and coarse samds. and ground up asphalt. All are for different surfaces, and all do an excellent job on the materials they are meant for.
Get the blasting cabinet first, then match the compressor to it. As was said by other posts, You will want a large volume of air, so make your purchase accordingly.
+1 on the reserve air tank.
If I have to explain why I ride, you wouldn't understand. Explaining sex to an alien would be easier than explaining the feeling, one that boils all that is going on in your life down to what really matters each time you are in The Wind. All I can say is, Life is not Life without it.