NO
Try the on line auctions like auction arms and gun broker, there are pictures of them there. You may have to look in the archives, but there are several pictures of many models.
yes
Being an in line you should have no trouble with pellets.
Check the on line auctions.
To even begin to give an accurate value I would need to know the condition, maker and model. If you don't know these you can compare yours to ones in the on line auctions, like gunbroker and auction arms. Look up black powder pistol or black powder revolver and compare photos to what you have, that should help identify and give you a value as well.
Without knowing the maker or model it would beimpossible to give you an accurate value. I can however steer you in the direction or the on line auctions such as gun broker, auction arms and guns america. You can search black powder revolvers and compare what you see to yous. That may help with the maker as well as the value. The PN you mentioned to is a Spanish proof mark (polvos negro in Spanish) or black powder.
gun shop, gun show, want ad, on line auction
You must to be 18 or over in most places. There are a few places that require 21 and or a permit to buy black powder. If you have a question about your specific area you can contact a distributor in your area via this website www.goexpowder.com/distributors.html
Most .50 Caliber rifles ,[ in good condition] can handle 100 grains of black powder. Some new in-line models can handle up to 150 grains.
$50 to $150 is what I have found on line
Manufactured by Simonis, Janssen, Dumoulin & Co around 1900. Should be worth $150-$250 as a mantle decoration. Don't try to shoot it unless it has been checked by a competent gunsmmith and then only with the proper (short black powder) shells which you CANNOT get off the shelf at Walmart.
The ants can't cross the line of powder.