I own well over 70 different air guns and rifles and I NEVER leave the C02 in the guns. The pressure can ruin the seal on the older airguns if it sits pressed up against the seal too long.
Co2 comes out of a bb gun because of the compressed co2 cartridges that are used to propel the bb itself. Additionally, the bb gun that does not use co2 cartridges just doesnt shoot out co2, but air in general.
Only if you don't want it to fire. Actually it is best to store the gun without a C02 powerlett in it.
No it won't fire, Co2 is the power source that power the gun.
No
If it is inside and the BB doesn't leave the building. It is against the law to shoot your BB gun outdoors.
No
In the truest sense of the definition of "automatic", no a bb gun cannot be automatic. In function, however, a BB gun can be automatic. A good example would be the Drozd BB gun which fires full automatic, but used CO2 as the power source.
Co2 will leak out in a few hours. It's not designed to stay in the gun for a long period of time.
You don't magnetize the BB's. The Magnet is inside the BB gun. The gun has to be taken apart and the magnet that holds the BB's replaced. Not all designs use this method of holding BB in place.
at the nearest store
YES! Especially CO2 systems.
I would try a sporting good store, Gun Store, or the web.