CFM= Cubic feet per minute. SCFM= Standard Cubic Feet per minute (CFM at standardized conditions). I think manufacturers intentionally throw these different terms out to keep the consumer from comparing apples to apples.
Blasting units are probably one of the toughest tools for a compressor. They hog bunches of air. Take a look at the tools that you are considering buying. They should give you an idea of the amount of air they need to operate efficiently. If you buy a compressor for the blasting units, you should be good for most anything else you want to run.
Another thing to keep in mind when you are purchasing your compressor, is the attachments you will need. For a compressor of that size, you are probably going to want to plumb an air line and a drop at least 20' from the compressor. This is especially important if you plan to pant at some point. You will need to put a good filter on the line at the end of the drop. And of course you will want air hose and connections.