Air Compressors - mainsplain

[truckster]

Horsepower matters because something has to drive that displacement. The more horsepower, the more air the compressor is capable of displacing in a given time (cubic feet per minute). If you have a displacement that is too large for a given horsepower, the motor either won't turn or it will burn up really quickly.

I don't know the answer to your second question.