Pumping up the air!

[Gary S]

If we are switching out industries, what is the process used when cars are coupled onto the train? Woould we connect the air hoses and pump up the system for every move no matter how short? Is it correct that the brakes are released only when air is in the system? Would we ever keep the air in a car's brake system to keep the brakes released even though not connected to a loco?

Any info you guys can provide on how a real crew handles the air would be appreciated.