Try Numrich Arms
Barrel, stock,
it just depends on what gauge and the stock and other stuff like that?
Try e-gunparts.com
If it is a typical Stevens double or single barrel there should be a metal lever towards the back of the stock slide it left or right and tilt the barrel down.
between the stock and the barrel
Lock stock and barrel
The serial number on a 16 gauge single barrel Crescent shotgun is typically located on the underside of the receiver or on the tang, which is the part of the shotgun that connects the stock to the action. In some models, it may also be found on the barrel, often near the hinge or where the barrel meets the receiver. If you're having difficulty locating it, ensure the shotgun is unloaded and inspect all accessible areas carefully.
Hang it over a fireplace.
I have a nitro hunter 12 ga serial 555281 $50 for the whole gun
online
Yes.
Length of the stock determines "youth" designation, not barrel.