Not legally.
A gun part is not a regulated item. However, the frame of a firearm, known as the receiver is legally a firearm. A convicted felon may not possess a firearm, nor may they possess ammunition.
NO
Federal law states that it is illegal for a felon to posses firearms or ammunition.
Yes...
No. A convicted felon is a convicted felon regardless of WHERE they go or live in the US. Note: Use caution if you're even thinking about it! The federal punishment for felon in possession of a firearm is a minimum of 15 years in federal prison.
HIGHLY illegal.
A convicted felon may not purchase, possess, or have access to firearms ANYWHERE in the United States as per federal law.
No.....
YES
Provided you are not a convicted felon, you can buy long guns at 18 and hand guns at 21.
Under federal law, applicable to all states and territories of the United States, a convicted felon MAY NOT purchase, possess, or be allowed access to firearms.
You need to consult with a lawyer familiar with firearms law.