Each state has it's own laws concerning handgun purchases (each country too). The best way to find out what your specific state requires is to look it up in the books, or on the internet, or the old fashioned way, ask a local cop. I think most states at 18 years old you can buy a handgun by yourself. Actually, asking a local cop is not a good way to find out about handgun laws. Checking with a reputable local gun store is usually the easiest way, but that's beside the point. Regardless, there is no such thing as a cosigner for a handgun. Most states (but not all) allow people under 21 to own or possess a handgun, and handguns can be given as a gift as long as the receiver qualifies to own the gun under their state laws. If your state law allows ownership of a handgun under the age of 21, you can purchase a handgun from an individual, or have a parent purchase the handgun from a licensed dealer for you as a gift (to be legal under federal law, it has to be a legitimate gift).
By using his parent/guardian's address, but his name on the envelope.
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.
Can a parent legally kick-out their 17 year old in Michigan ?
No, and that's federal law.
Yes, a twelve year old can move in with the other parent.
You need to get a judge to expunge your records.
Yes they can.
a 27 year old woman.
Then the parent of the 21 year old must want their kid to go to prison for some reason.
Yes.
No, you cannot.