Yes,the Xbee wireless is on a bluetooth frequency, some of the more powerful ones have a 1 mile LOS range.
The Arduino board is a computer programmed logic controller board with (depending on model) several Analog I/O's and Several Digital I/O's as well as a few can be configured as PWM (like servo commands). I've been toying with the idea of making my own Radios if I ever get around to building my own large scale RC equipment. I believe you can even use them with a wireless PS3 controller as well But in your case I would hook up the real controls.
I got this book several weeks ago, is well written and easily understandable. I think if you can handle G-code for the cnc you could handle programming an Arduino board (2 in this case).
http://www.sparkfun.com/products/9301
Here's a vid of them.
http://www.youtube.com/watch?v=KxtI7_UQGTw