Either or, most people do it alone and switch between positions. There is level flying autopilot for when bombing and it remembers the last input of the joystick so if you want to slowly turn in a direction while using the rear MG you can. Multi-crewing is some of the most fun you'll have in game though if you get a good guy on team speak to do it with you.
Both sides have a dedicated TS channel with a HC room and a room for each bde (generally each squad belongs to a particular bde so they hang out in there).
I play most days when time allows. Be careful though as there are days where I'll throw it on in the morning just before breakfast then suddenly it'll be 6pm and my stomach will clench so hard from not having food that I almost fall off the chair =/
