Contact Browning.
Your browning superposed was made in 1933.
With the serial number that you provided,your Browning superposed shotgun was made in Belguim for Browning in the year 1955.
Superposed
'*' designates full choke (F). '*-' designates improved modified choke (IM). '**' designates modified choke (M). '**-' designates improved cylinder choke (IC). '**$' designates skeet (SK). '***' designates cylinder bore (CYL).
Your browning superposed was made in 1968.
Yes. A lot of choke manufacturers like Briley will also. Check with a gunsmith in your area as some have become really good at it.
Receiver
No, they are not.
The 72S suffix to your serial number indicates that your Browning superposed shotgun was manufactured in the year 1972,by FN of Belguim for Browning.
Browning can tell you how it left the factory, and the gun can be dated by serial number.
Impossible to tell without pictures.