The information your looking for can be found on the High Standard Collectors Association web page under links or Google "john stimsons high standard data",hope this helps
your Winchester model 12 shotgun was made by Winchester in 1959.
Impossible to answer without knowing which model.
The Marlin model 24 shotgun was produced by Marlin from 1908-1915.
your Winchester model 12 shotgun was made in 1940.