You can be any age with your parents consent, but you must be 18 years old to purchase one.
At least 18.
18 for a rifle or shotgun, 21 for a handgun.
21 for California.
no
Buying a gun from a dealer is controlled by Federal law- 18 for a rifle or shotgun, 21 for a handgun.
In general, any felony makes you inelligible to own a handgun.
I don't know about California, but in most states there is no official gun registration. You can carry a handgun in California if you have a California handgun permit, but I understand those are hard to obtain in some counties.
MONEY and JAIL (mostly)
No.
To legally purchase or own a handgun, you must be 21.
One is 6 months old, one is 120 years old- but we can't answer your question. Please rephrase it with some information on YOUR handgun, and repost it.
21 years old
21