I would like advice on compressors as well. Even at 10 psi, my motor has thermal shutdown on long carves and it is a brand new high-end Kobalt unit. I do not think regular compressors are designed to spray air constantly over time. Maybe a good airbrush compressor?
I use this device and it works great:
https://www.amazon.com/Coolant-Lubrication-System-Milling-Machine/dp/B015545SWA/ref=sr_1_1?ie=UTF8&qid=1481656387&sr=8-1&keywords=cnc+mister
I sprits with WD-40 once or twice during cutting, just to prolong the life of the bit, but the chip clearing is the real key.