Either a full choke,or extra full choke shotgun barrel.
Is it a screw in choke?
Most ARE shot from full choke- or even Extra Full Choke.
That will depend on whether the choke tube is rated for steel shot or not.
If it was made to shoot steel shot and has interchangeable chokes.
That will depend on whether the choke tube is rated for steel shot or not.
No.
You will need to shoot both chokes with as many different kinds of ammuntion as you can afford at the range you intend to shoot. Your shotgun will show a preference for at least one load.
stupid nobody knows the answer to that.
NOT RECOMMENDED unless you are in a life or death situation.
Yes.
As long as the barrel was made after 1950 and does NOT have a full choke, you will be able to shoot steel #2 or smaller.