No. Aspects which determine how powerful an airsoft gun is actually it's spring (stronger/harder the spring means bigger fps), compression (better compression = better fps), and weight of the BBs we use (heavier BBs in the same fps can deliver bigger energy).
Edit: If a gun that is automatic in real life is spring and very inexpensive, it is probably cheaply made and therefore almost definitely weak. However, "manual" guns that are spring are usually at least fairly powerful, such as bolt action sniper rifles.
A BB gun would be more powerful
No
Neither
No company makes a spring action galil airsoft gun currently.
Self protection? As in keeping robbers away from your house? I guess i would go with a gas rifle. They are often the most powerful, but are more expensive. If your are looking for home security, an airsoft gun would not be your best bet. I would go with an actual pellet gun or air rifle. Airsoft guns are more for recreation.
No. even though some spring guns have great range, co2 allows you to fire more then once before reloading.
go for the m14, unless its cheap looking.
No, it is a cheap spring gun and could not be used in an airsoft match
A spring gun? It depends on how fast you can cock the gun. There is not a fastest gun.
The more powerful the batter just means the longer your gun will last before it has to be recharged. 'Fox Airsoft Store' offers some gun upgrades, these will improve your gun. Also, a gun's fps is already pre-determined by what parts are installed, upgrades will improve the gun but stronger batteries will only extend the gun's life before it needs to be charged.
Not sure what the question is, be more specific, each gun has its own magazines, and spring guns suck if not bolt action rifles or shotguns.
NO!