FIE imported various arms made by various makers.
Colt
Gun shop, gun show, want ad
Check Blue Book of Gun Values
Want ad, pawn shop, gun show, gun shop
50 USD
gun shop, gun show, want ad, pawn shop, egunparts, MidWay USA, Brownell's
Not in any of the gun books I have part of one
Probably not- sorry. FIE was the importer, guns made mainly in Germany. Company is long gone, and my main source for obsolete parts (Numrich gun parts corp) has none for that gun.
At a gun shop or gun show. <><><><> Additional- FIE was an importer of mid to low quality firearms, and is long out of business. Despite the name, none of their .25 autos would really be a "best pistol". Walther, Browning and Colt did make good quality .25 autos.
$25-$70, depending on condition. Imported by FIE, amde by various Euro gun makers, generally low cost, indifferent quality.
It was made for marking trees
If you have the Standard revolver, this is a "pull pin" type action, where the cylinder pin slides out the front, and the cylinder is removed from the gun to be loaded. For further instructions, I would recommend you to your local gun shop. While you are there, ask them to examine the gun to see if it is safe to fire. These were not especially high quality firearm- the retail value of a used FIE Standard is below $100.