Have you done any 3D printing before?
W.r.t. firmware, you’ll need the version with the extruder. I don’t know what Ryan ships, but I’m guessing if you bought it with the extruder, then it will be the right firmware.
I’m not 100% certain on this, but you’ll either need a resistor to fake out the temp or you’ll need to keep your hot end plugged in when not printing
If you haven’t printed anything before, I just want to warn you. The mpcnc is not the easiest way too start. With your background, you’ll be able to do it, but just go in with a lot of patience. I won’t write a guide, there are plenty of generic 3D printing guides (take a look at the rep rap wiki). I will tell you that 90% of printing is getting the first layer right and 9% is getting your slicer setting right. Lucky vicious1 had some decent starting settings. Just go slow, follow one of the calibration guides, and be patient. You can/should post images of your failed prints for help.
Looking forward to see what you mill. I bet you make some great stuff.