No you can't. almost every different manufacturer uses different types of threading on their barrels. Be sure to check and make sure your barrel is compatible with your gun before buying. Sometimes you can buy small adaptors for the base of your barrel that have one kind of threading on one end, and another kind on the other, so that you can use a barrel that wasn't made for your gun.
No, any tank will work.
Any gun with a High Pressure System (which is basically all of them) can use this tank.
Dicks, any paintball shop, and Gander Mt.
Yes, you can use any size tank
you need Co2 to fire any paintball gun, it is what physically moves the ball out of the barrel.
No.
Where the air tank or co2 tank normally attaches
Yes, the largest CO2 tank, the 24 oz can fit on the Brass eagle Raptor or any marker for with standard ASA threads. However not every marker can use Co2.
The sizes 9 oz and all the way up to 20 oz can be used for paintball gun. Some of the paintball guns are supposed to be used by the larger tanks. So the size of tank depends on your paintball gun.
yes
There is no paintball gun that runs on only 200 psi.
unscrew the tank, this will vent any co2 that is in the marker out the asa