Not without modification.
Man Without a Gun - 1957 Eye Witness 2-2 was released on: USA: 1 June 1959
Man Without a Gun - 1957 Witness to Terror 2-4 was released on: USA: 9 June 1959
None. It takes no modification to fire a pepper ball out of a standard .68 caliber barrel
No
No.
No. Yes. All you have to do is strike the bullet's primer with a sharp corner of the gun.
without CO2 or paintballs, you just put the bolt forward. In most guns this is how you de-cock after a day of play, but if you have a regulator, it may store a single shot. If you fire without co2, the gun will not cycle or fire a paintball, it will only go into the barrel. If you fire with no paintballs and co2, you may damage your gun.
dry fire it without any BB's
Yes. If you keep firing your gun without any lubrication, the O rings will eventually wear down and your gun will leak or cease to function.
It depends on what you mean. You can fire a gun anywhere, however, it may or may not be legal depending you where you are and what the local gun laws are AND it may or not be safe, depending where you are. Check your local gun laws and be sure you can safely fire the gun without damaging any property or other people.
No, and you can't drive a car with no fuel. A gun is a device to launch ammunition. You can "dry fire" a gun with no ammo, but that is not good for SOME guns.