A:AnswerFrigidaires' website reports that it is 57 dB on low, and 60 dB on high. Though it does not state if that is inside or outside, I'd think it a pretty safe bet that is inside sound measurements.
A:AnswerThe best setting for maximum cooling is to have the outside air vent closed. If you want to introduce fresh air into the room, open is the way to go. You can also use the ac on the "fan only" setting with the air vent open to draw in cooler outside air, if desired.