In my quick read, this looks like good advice all the way. The only thing I might add is that 220V services are dedicated -- one breaker, one load, one outlet. Everything sized properly all the way. If this thing is to be plugged into the service, rather than hard-wired, you need to match the plug/outlet to the load. Unlike most plugs in your house, 220V plugs come in amperages that match the load. You can't plug a 30A dryer into a 20A or 40A 220 service. This give one more layer of safety and for 220V, you need it all.