Yes to both questions.
If this is a browning a-5 shotgun than 1929.Change that year to 1926.
Best left to a factory trained gunsmith.
1945
Just before WII.
Shimming to change the comb is tricky business. Recommend you contact the Browning Service center for advise. Use the link below for your convenience.
Go to the Browning link attached to this answer. Be sure to print it out and save the drawing. Many people glue the drawing on the inside of their forearm where it won't hinder the barrel and recoil spring.
With this serial number it would have been made in 1926. If there is a letter above or preceding this number it would change the date.
A Winchoke is a screw in choking device that screws into the end of a Winchester Shotgun. Commonly called a screw in choke, most manufacturers have a different name for their chokes that they made specifically for their products. Screw in chokes eliminate the need for extra barrels with different chokes built in. The screw in choke allows the shooter to change from open chokes to a full choke depending on how wide they want the shot pattern to spread. Winchester makes the Winchoke, Remington makes the Remchoke, Browning makes the Invector choke and so on.
It is both- the browning of the crust is a chemical change as well as any other browning. If the filling simply boils and loses moisture ,that is a physical change.
You need the services of a Browning trained gunsmith
To change the choke of the shot
Leave this to a qualified gun smith.