Well, 5, cause 3 ain't enough and doesn't survive the arena generally.
Concerning the landing and re-arming; I heard that someone bombed and bailed because its easier to start with a new set by doing that.
Surviving in the MA with buffs is easy.... ask most fighter guys how much the like going after buffs.
Tips, fire all guns in short bursts.... unless the guy sits 300 off your tail then light him up!!!
Use alt as your friend. 15-20 only the most determined players will chase you down, over 20k very few will bother.
Fly with friends, a group of two or 3 buffs in a tight formation is VERY formidable.
Most people who bomb and bail are just looking to get bombs on target and points/lives/nothing but damage matter. If that is how you want to play, go ahead. If on the other hand you want it more "realistic" plan your route, get to alt, and return to base when your empty.