Hard to say. Forehand Arms name was used only a few years, starting in 1890. 1887 was before that- you may be looking at a patent date. In any event, there is no ready source of "off the shelf" parts for these. A competent gunsmith can MAKE a spring for one. However, please consider- these were inexpensive guns when new (sold for $2.98 back then- really) and were made to fire black powder cartridges. You could possibly spend $100-$250 to have a spring made and fitted (depending on cost of smithing in your area) and you would still have a $50 revolver that is unsafe to shoot.
Forehand & Wadsworth changed their name to Forehand Arms Co. and was eventually taken over by Hopkins & Allen. Unfortunately without the serial number it is hard to narrow down an exact age. I can tell you it was produced between 1887 and 1915.
The Bulldog
Blue Book of Gun Values might have something.
I could not find any 380 cal. pistol going back to 1887 ??? are you sure it's not a 38 cal. revolver ???? check writting on top of barrel ......................
10-1000 USD depending on specifics
1887
Can't be answered without knowing if it has the box, papers, accessories, caliber, finish, condition, etc..
Somewhere on the frame.
Depending on the condition of the pistol. Here is one in rather poor condition for $ 1095.00 http://www.collectorsfirearms.com/admin/product_details.php?itemID=19473
Impossible to answer without a detailed description of all markings.
Anywhere from $350 to $800 dollars depending on the year it was made and the condition it is in.
Impossible to answer without at least knowing the manufacturer and model... sales@countrygunsmith.net