yes they are refillable
No they can e damaged by water
Nearly everything. Paintball guns are fired through the use of air or CO2. Also they shoot only paint. bb Guns shoot pellets, and look completely different then most paintball guns.
Where the air tank or co2 tank normally attaches
drain the tank, throw it away
Co2 is carbon dioxide that is used for paintball guns
It depends on the specific marker, pump has little to do with it.
Yes, infact it is recommended.
Paintball guns can use Co2 from any company, they are all built the same. You can find valved tanks and 12 gram's at sporting stores, paintball fields and proshops.
On a paintball gun C02, or High pressure air is necessary. It is compressed air that, when the trigger is pulled and the marker fires, propels the paintball out of the barrel.
Remotes allow to mount your air or co2 tank of your paintball gun.
You must have them hydro-tested or throw them away. You will not be able to fill them legally.