You will have to contact the California Department of Justice for a current, legal and correct answer.
No.
yes
Yes. An air rifle is not considered a firearm, thus a felons possession is not limited.
Yes, an air rifle is not considered a firearm by Texas or federal laws.
When you say Air Rifle you are referring to a pellet rifle not a firearm. At present there are no 300 Cal air rifle being made.
Only if the scope is designed for air rifles. Regular firearm scopes are made different than air rifle scopes and many will break if used on an air rifle because the recoil is different than a firearm.
No. Not yet.
No
If it is BB or a pellet gun, yes. A real firearm, no.
All states have some laws pertaining to air rifles. An example is, you must be 18 to purchase an air rifle in California.
The minimum age is 17 for an air-gun (rifle or pistol).
If it fires a projectile, it is classified as a firearm and you will need a licence for it. Your local District Firearms Officer will be able to advise you in more detail.