The question is to broad and vague to be answered. You have to define what it is you are going to do with the hand gun, i.e., hunting, target shooting, collecting, self defense.
Gun store.
Once can purchase a hand gun safe from a variety of different places. Some large gun stores sell hand gun safes. Stores specializing in security will also be able to help.
Hand gun - 21; long gun - 18
At a minium, 21 for a hand gun and 18 for a long gun.
21
No
To purchase a gun, no. Anyone can purchase a gun as long as they meet the age requirement, aren't a felon, and don't have any disqualifying misdemeanors.
You can't. Only a LEO or LEA can.
In the United States, yes.
18 for long gun, 21 for hand gun
18 or 21 depending on if you are buying long gun or hand gun ammunition
You can look for them at gun shows, gun shops, or you can try finding them on e-gunparts, Auction Arms, Gun Broker, Guns America, etc.