100-500 USD
100-1000 USD depending on EXACT variation, box, accessories, papers, history.
1924 was the first year for wood grips. 1924
The 132 came with plastic or wood grips. Some of the plastic grips had Checkering, however I do not believe the wood grips ever had checkering.
The correct grips for a BHP Capitan with a serial starting in "73c" would typically be plastic grips. However, it's possible that wood grips may have been installed by a previous owner. It's best to verify with a trusted gunsmith or contact the manufacturer for confirmation.
Wood
Try e-gunparts.com
No. Not English ones anyway, they were made of wood.
100-460 or so
Impossible to answer without a detailed description of all features.
Depends on when it was made. Usually you see Walnut and Goncalo Alves.
There were no grips made for CD/M shotguns. Butt stocks are one piece, whether they are pistol grip or English style.