I have a spindle and variable speed controller that I can pre program in my CAM. No issues with Mach, just took a while to get the ratios right so that the spindle was spinning at the speed mach thinks it is, however that was done on the controller from memory and not mach. No issues with changing spindle speed my remote control though mach or anything that I can think of. It's been a few years now. I cannot remember what brand the controller is off the top of my head.
My spindle can be run air or water. Air cooling is useless in the Aussie summer, we tried that first, even the water gets really hot and the temp of the spindle rises which means the cutters stay really hot and it makes the tool changer play up/stick. If you go a cooled spindle that it can be water cooled.