Depends on the law WHERE YOU ARE- and you did not share that with us. In MOST of the US, a license is not required to buy a handgun from a dealer. If you can repost, and give us a state or country, we can try for a better answwer. Sorry-
No, you do not need a gun license to buy magazines.
No
yes
No it's not necessary.
No.
no
no
You have to be 18 to buy a long gun and 21 to buy a hand gun.
Yes, you do not need a gun license to buy a clip, but you may need one to legally possess and use it depending on local laws.
yes, you just need a license
Generally, no.
Laws on this vary by jurisdiction.