in auto the bags will do their best to maintain ride height & a level ride.
dropping the jacks (or raising the coach) will let air out of the bags (as it raises the frame)....this is normal.
when breaking camp you should RAISE the jacks (lowering the coach), then start the coach and let the bags fill until the compressor cuts-out (or shuts off).
each time you press the brake pedal you use some air from the tanks (press harder and you'll use MORE air)....once air pressure drops below 100 or so lbs the compressor will cut-in (aka turn on) and refill the air tanks (to about 130 psi) where once again the compressor will cut out (aka turn off).
your brake air supply is based on the PRIMARY air pressure gauge.
the airbags are usually represented by the SECONDARY air pressure gauge.