Caramelise.
YEs
Those imported into the US with the Browning name (since 1956) have had varnished and later polyurethane stocks. Early guns with the FN markings had oil finish stocks.
No
No data available
No
Send it to a Browning authorized repair center.
I would contact Browning directly and see if they have any in stock. I would also look at Boyd's rifle stocks and see if they have any reproductions that would fit your Browning.
Sometimes they will within a particular model.
Browning did not use salt, their supplier did. Check any item made before 1976
Any good stock maker.
Contact Browning, try e-gunparts.com, any of a dozen stock makers would probably make you one.
Generally, yes.