It's really not recommended. By doing so you leave the gun pressurized and this may rupture the seal. It also makes it possible for someone else to accidently fire the gun.
Read the directions for YOUR gun. CO2 does not explode, but may leak down.
If it is a gas gun, no. However, some are spring guns, and some are electric.
Yes, once it is in, you can not take it out and use it later, as it is not resealable.
Yes, hotter Co2 expands faster than cold, but only if that temperature is constant, but heating CO2 tanks is extremely dangerous, and will not do anything but weaken the cylinder, which may explode and shrapnelize.
It depends on the model
Gun shops, gun shows, want ads.
They will usually leak out over the next 24 hours but may take longer. If you keep doing this the Co2 will eventually blow a seal in the gun and render it useless. Never leave a Co2 in an air gun after you have used it. Most BB guns get anywhere between 60 to 80 shots from a Co2 cylinder.
No it won't fire, Co2 is the power source that power the gun.
The CO2 will be depleted and you will not be able to shoot anymore. If you leave a full one in there for a long time, it will slowly leak, or could damage your gun, so you should remove it after each game day.
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.
Well no a Co2 cun justs uses compresed Co2 intead of a spring or a batery Co2 if fairly cheap and are easy to use
A paintball gun needs CO2 (or HPA) to fire at all.