In the area of $20-$40
~$30
"H" is not a size for CO2 tanks
No, any tank under two inches in diameter does not need hydro-testing.
No, paintball co2 is much higher pressure.
It just depends on the tank size, temperature, gun efficiency and how much you shoot.
A 50-pound steel CO2 tank typically weighs around 30 pounds when empty.
Depending on the quality of the tank, it will take around a year to deplete a 20 oz tank. As long as you don't drop it on the valve or put it in the oven, you can keep it functioning until the re-hydro test date.
CO2 tanks are not rated of the amount of pressure they put out, but the size of the tank and how much weight of CO2 it holds. This is because CO2 pressure changes rapidly with temperature. It is on average about 1000 psi.
There are two ways to test if your Co2 tank is a siphon type tank. (1) Look on the side of the brass valve for either an "S" for siphon or "DT" for dip tube that would be used to draw the liquid from the botom of the tank. Either of these would indicate a shipon type valve. (2) If you do not find the "S" or "DT" on the valve there is a good chance that it is not a shipon tank. You can do a second test to verify this. With the tank upright and securely supported, open the valve and watch the discahrge. If it looks like snow and falls to the floor you have a siphon tank. If you get just gas and no snow, it is not a siphon tanks. Caution Co2 is very cool and and burn skin. Be sure to protect yourself when performing this test.
CO2 is not used in or as an aircraft fuel.
Usually between $5 to $10.
No paintball gun will work without a CO2 tank or other propellant tank. without Co2 there is nothing to push the ball out of the barrel.