Yes. See related links for an example.
No
Depends entirely on the magazine. Some are not meant to be taken apart.
Yes
Drop the magazine and clear the chamber.
Lever Action Magazine Pistol
No
Try egunparts
You will have to find someone who specializes in air gun repair.
No such thing ans a "magazine clip". If you want a magazine for it, contact S&W or your nearest gun shop.
If someone has made one.
50-325 usd
A shotgun made for Smith and Wesson, sold under the Smith and Wesson name.