Depends on the laws where YOU live. Your spelling of licence may indicate that you are not from the US- in other countries, pellet guns above a certain power may require a licence. You will need to check with local law enforcement for your area- sorry that we can't be more precise.
Nope. Pellet guns are fairly safe to use.
Not in the United States
Contact your local police
No ... but their may be an age requirement.
It depends on the model and the caliber of the Pellet gun.
Are you trying to fit on a gun or rifle ( you said gun) What model are you asking about,. Is it a scope designed for pellet rifles. How big its the dovetail on the rifle. You need to be more specific.
I think you mean pellet gun. That is a gun that fires a small lead pellet but does not use gun powder. It uses compressed air or compressed gasses to push the pellet.
A pellet gun is not adequate for protection, and will get you arrested.
It all depends on the model and who made the pellet gun. I suggest that you re-post the queston with the model and make of the pellet gun to get an answer.
Any pellet gun should be handled like a real firearm. Yes you can be killed with a pellet gun under the right circumstances.
Best left to a trained person.
350FPS would be sufficient