Well water for cooling is fine, since the spindle housing is a high, chrome, nickle, low carbon content stainless steel tooling grade, from a glance. I here guys are using the mix with rust inhibater also ok, not sure its required but hay?
The breakout board is the board that u plug the USB or db25 connector into that talks to the computer and program Mach3 or equevelant to send signals to the stepper drivers cards for the motors, you have one already installed in your controller, you have too so it works, no need to buy one you already paid for it.
Remember there are still more adjustments to be made on this machine to actually start cutting material. These settings are only to get you started, we all are on a learning curve here so play around with what you have now get real familer with the machine before you take the next step, unless your experienced different story Am just a hobbiest Am a welder by trade, this was not my job day in and out so I even have too step easy to get it right.
Well hey enjoy have fun its what its about
Later CHIMERA1960