I have no idea about the violin, but I did a little research on the shotgun.
According to Wiki.answers.com, the Hopkins and Allen Arms company took over the Forehand name in 1903 and continued until about 1915. You most likely have a single-shot hammerless shotgun called a "Forehand." Another website,
www.gundersonmilita ria.com lists a shotgun that sounds very similar to yours. It has photos and lists a price of $175.00.
Gun values are very difficult to determine. It really does take an expert and a physical examination to get an accurate value. I suppose yours could be worth more, but it would take a firearms appraiser to tell you for certain. Many guns are highly valued because of their uniqueness, their manufacturer, or limited production. I've never heard of this company before, so I don't know if the gun you have has any of these traits.
Good luck!
Sarge