Sometime in the first half of the 20th century.
If you are speaking of the single or double barrel guns, you can change barrels. However, you should have a gunsmith look at the other barrel to make sure it fits properly, most of them need a little hand fitting.
It was made in 1914 and "probably" is a Flues model
$50-$150, depending on condition. Most were low dollar guns.
Most shot guns can handle deer slugs.
Go to Numrich Gun Parts in google, they have online schematics for most guns.
Yes
made in usa
Check the yellow pages for gunsmiths. you can find any and all parts for almost all guns at www.e-gunparts.com
Some brands of the double barrel shot guns includes, Stoeger, Remington and Winchester. The price for the double barrel shot gun can range from over $1000, depending on the collection.
Marixa is a Spanish brand. Elbur is probably Eibar, which is a town where a lot of Spanish guns are made. It could be worth several hundred dollars.
You can get some double barrel parts from GUNPARTS. com