You'll need some kind of derailer hanger like this . I think you can get away with zip-tying a full run of housing (in the absence of cable stops) from the derailer to the shifter. You can use a clamp like this to mount a downtube shifter.

The website doesn't give the rear axle spacing. I don't know if wheel would need to be redished to fit a 120mm axle and a cassette.

I don't know how you would mount brakes on that. You could drill out the fork for a front brake? Not sure if the frame has a rear brake bridge that could also be drilled out. Again, in the absence of cable stops, you'd need a full run of cable from the brakes to the levers.