What type of switches do I need to do things like turn on coolant, switch axes for my mpg, and turn on/off other things in Mach? Can I use momentary switches or do I have to use continuous/toggle switches?

PS- my setup is G100 & Mach 3

Depends how you are interfacing them with the computer, I dont know about the G100 so cant say on that but if you have a keyboard emulator then momentary switches is what you want, if you are using pins on a port then toggle I would think.

Hood