No ... but their may be an age requirement.
Any age so long as you have adult supervision who know firearms.
If they are planning on hunting you should start them early. 9 would be a good age
It depends on the model and the caliber of the Pellet gun.
all you have to do is buy the gun after that do what you want
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.
In the Unites States you have to be 18 to purchase a pellet or BB gun, but you can be any age to shoot it under adult supervision.
A pellet gun is not adequate for protection, and will get you arrested.
There is no statutary limit on age for open carry. BUT you must have a gun permit which has an age requirement of 21 years.
Any pellet gun should be handled like a real firearm. Yes you can be killed with a pellet gun under the right circumstances.
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.
You can purchase .177 pellets at most any sporting goods stores. "Big 5,"' Dicks" or Wallmart just to name a few. As for the age of the Pellet gun you will have to give more information about the "GUN" (It not a rifle?) to determine the age. If you are asking about the model 177 then it was made between 1935-41