Not in the USA. If you live outside of the USA... maybe. Really hard to let you know what the laws in your jurisdiction are without knowing where you're referring to.
not in all places but here are some strict laws I would suggest talking to the local police
You don't need a gun license if you are 25 but if your under 25 you do need a gun license
No, you do not need a gun license to buy magazines.
You never need a license to have an Airsoft gun.
No, you do not need a license to purchase gun magazines in most states in the United States.
To get a gun license you would need to go into a gun store in the town you live in and ask for the information you need.
It shoots a slug instead of shot.
No.
yes
It depends on several factors; Where you are located and exactly what you mean by "gun license." Do you mean a license to carry a gun? A license to purchase a gun? A license to build guns?
You need to tell us more about the "gun license" and for what area. There are many different gun licenses.
No.