It all depends on how good the seal is but usually not more that a few hours. Besides it is not recommended that you leave a C02 powerlett in the air gun when you are finished shooting it will eventually ruin the seal if you leave it pressurized for a long period of time.
It depends on the tank size. the average 20 oz is about 800 shots.
Which model? If it is the t9 or t8 pistol then you have to buy an adapter for a 20 oz tank.
A 12oz tank will not last long on any gun. Most likely, you may get 400. 500 if the dwell is low.
It just depends on the tank size, temperature, gun efficiency and how much you shoot.
There are several factors that effect "HOW LONG" is. Temperature, How fast you pull the trigger. and how long the "powerlett" is in the pistol. It is best to say about 50 or more shots per powerlett. However never leave the C02 in the pistol when you are done. It will eventually leak out and may damage the seal if the pistol stays under pressure. Also it will prevent someone from picking up the pistol and accidentally firing it.
Typically the pistols are "12 gram" powerlets although there are exceptions. The owner's manual will tell you.
A keg can last about 6-8 weeks when using CO2 for dispensing.
Unopened CO2 cartridges can last indefinitely if stored properly in a cool, dry place.
Yes, any size Co2 or air tank can be used with the A5 and every modern day, as long as it has the standard ASA threads.
It all depends on the size of the tank. What size. 12 gram, 8oz, 12oz, 20oz or 24oz?
If you are asking about the Crosman C02 pellet pistol then Yes that is what it is designed to power the pistol.
No.