No, but you need to be the legal owner of that firearm.
A foreign citizen with established permanent residence may purchase and own a firearm in the US. <><><> In addition certain temporary residents of the US may legally purchase a firearm- such as for hunting. However, they must have a hunting license first. This is listed in 18 USC 922- and usually overlooked. Permanent resident aliens (such as my wife) that have a "green card" are treated as a citizen when purchasing firearms.
Yes, you do need to be a US citizen
Yes. You need to be a citizen of the state, too.
The word citizen does not need to be capitalized.
If you mean the purchase of a firearm from a dealer in the US by a person that is not a citizen or permanent resident of the US- not by itself. An non-resident alien LEGALLY present in the US may purchase a firearm under limited circumstances. They will need a minimum of two pieces of ID- one must be a government supplied photo ID that shows address- but you will still need to show legal presence in the US, or that you meet those limited circumstances for a non-resident- and a consular card does not do that.
does a citizen of Mexico need a passport to go from the us to Mexico and back? He is legal to be in us but not a us citizen.
Yes, you do. But you can't be a citizen of any American nation. You have to be a citizen of the US.
no they accept anybody that is citizen to US
If you are referring to a non-US citizen visiting the US LEGALLY, they MAY purchase a firearm for a legitimate sporting purpose, such as hunting.
Yes, definitely. You do not need to be a US citizen to bring a lawsuit in the US court system.
when does a us citizen need a passport to drive to Canada
No