If we are talking about a browning auto-5 shotgun? then it was made in 1956.The value of a standard weight auto-5 which you have,is selling for between 350-500 dollars depending on the overall condition remaining on the wood and steel.You could expect a additional 50-75 dollars for the second barrel that goes along with your shotgun.
No
Browning's web site has the current information.
The Browning web site has a search function that will assist you.
Try browning.com
To change the choke of the shot
Not unless it is threaded for them.
Yes
Look at the choke tubes.
If not OEM, yes
Yes, in the new A5.
The Browning made screw in chokes were available for most choke sizes
Should be interchangeable with Winchester chokes. http://www.choketube.com/guide.HTML Used browning invector chokes in my condor 1 o/u