Minimum Air Compressor Size

Most everything above is Spot On! The Sub Panel would be the way to go. How far from your main to the Garage? Voltage drop.. Man, it's actually Easy stuff. You could do it without anyone. Just do a Lil research. I HAVE seen people go to City Electric/ Greybar/ ect and custom build cords for Welders and Generators... much less cost than Home depots garbage materials. Anytime I can hit a specialty warehouse, I'm there!