There's no law that I can find specifying a requirement to have sights. Why you'd want a handgun without them is beyond me, but to each their own.
Generally it is 21.
21
18 for a shotgun/hunting rifle, and 21 for a handgun.
Yes
No. As of 2010, Arizona allows anyone who can legally own a handgun to carry it, openly or concealed, without a permit. Before then, you could carry openly without a permit, but not concealed.
NJ requires licensing of handgun owners, and police approval of all transfer of ownership of handguns. You need to discuss transfer on an inherited handgun with the NJ State Police.
It depends on where you are. In the U.S. 11 year old children cannot own a handgun, but it is legal under federal and most states' laws to possess the handgun for legal purposes such as hunting and target shooting.
Depends. Rifle or handgun? The Florida law addresses handgun ammo. See link below to the Florida ammo law.
In most U.S. states, there is no specific minimum age to use a gun for legal purposes, but a person does have to be 21 to legally own or purchase a handgun.
Arizona is an open carry state. If you can legally own a handgun, you can carry it openly without a permit. If you want to carry a concealed handgun, you need a permit.
With the approval of your parents, at any age. On your own, 18 for rifle/shotgun, 21 for handgun.
It depends on the circumstances. Where are you? Are you a felon? How old are you?