Yes, if purchaser appears to be under 21
in a gun store
Yes, in the US. Federal law requires you to be 21 to purchase ammunition for a handgun. .
That depends on where you live and how restrictive your local regulations are, but any sporting goods store will carry a variety of ammunition. Most Walmarts and many pawn shops have a sporting goods section. By federal law (in the US) you must be 18 to purchase ammunition for a rifle or shotgun and 21 to purchase pistol ammunition.
Fire ammunition.
if the firearms is deemed (discribed) as a pistol then you would need a permit to purchase.
Yes.
any sporting goods store. 9 mm ammo.
A pistol by loading ammunition into the chamber. The firing the pin then strikes the cartridge, which causes the pistol to discharge.
A 35 MM bullet would be about 1 2/3 inches in diameter. There is no such pistol ammunition. If you can give a good description of your pistol, I might be able to identify it and suggest the proper ammunition.
It is available if you look.
Full Metal jacket.
eighteen for shotguns and rifles. twenty one for pistol and its required permit