In general, if you are a law-abiding citizen over age 21, you can own a firearm. There are certain local exceptions such as New York City, Washington, D.C. and Chicago, but even these are being litigated.
Don't do anything stupid with it.
If you plan to purchase a gun, I recommend that you take an NRA-certified safety course (you can find those through your local firearms dealer, sporting goods store, or shooting range) and try several models. Any decent firearms dealer will ask you why you want a gun, and what you plan to use it for; this is so that he can suggest the best gun for your purposes.
No, it is not illegal. The right of law abiding adults to own a gun is guaranteed in the US Constitution. The local laws referred to below have been overturned in court.
No
yes it is illegal to own a sawed off shot gun in pennsylvania...as far as i know its illegal in every state of the US
Yes it is illegal to own a gun that does not have a serial number. It is also illegal to remove the serial number off a gun.
Not unless there is a local law that says you must.
Depends on the law where YOU are. In MOST of the US, there is no requirement or procedure to register a gun- popular belief notwithstanding.
It is not illegal to own ammunition but you must have a permit to own a gun.
It's illegal for a minor to buy a gun anywhere in the US.
No
In the US, it is illegal for some people to own a gun- convicted felons, persons that are mentally incompetent, etc. The background check is to insure that you are not a prohibited person.
No
It is not illegal. There is no permit required to own a firearm.
Yes, a convicted felon can own and airsoft gun and/or a BB gun. It is a real gun that convicted felons cannot own, in which this would be illegal.