18
Yes
It depends on local legislation.
Money. Permit not required.
Yes
No.
The answer can be yes, no or maybe. You need to consult with a lawyer and explain ALL the facts of your situation.
You only need a license if you wish to wear a handgun openly or concealed (it is illegal to do either without a permit). But no permit is needed to buy or own any otherwise-legal gun (rifle, shotgun, pistol) or to carry a rifle or shotgun.
As long as you meet the minimum age requirements and are not criminally prohibited, no license is required for a shotgun.
You have to be 18 to buy it. You need to talk to a lawyer about the "own" part.
Obvious don't you think
Depends specifically on what the misdemeanor is. Most will not prohibit you from owning or purchasing a firearm. Some will. For example, any domestic violence conviction will do it.