I can’t comment on the wire type, but you may be interested in this thread I made recently: RAMPS 1.4 Spindle Speed
The short of it is I’m not sure if the PWM signal is able to control the spindle, so I’ll be using an RC filter to smooth it out to analog and a voltage divider to step down the 12V to 10V from my RAMPS. I’ll be actually trying this out soon, so you can wait until the results of my setup if you want.