Yes, I have actually done this myself. I was out hunting with my cousin and I thought he was a deer. My instincts kicked in and I shot a slug straight at him. Luckily, I'm a very poor shot and I hit his model 1000 instead of him, but let me tell you, the slug went right through the gun and kept on going. So yes, it is very easy to shoot a slug through a 12 gauge model 1000 Smith and Wesson pump shotgun, as that's the exact model my cousin Darrell had been using. I don't know why you'd want to do this, but I guess you can do whatever you want with your guns.
Yes. You will have to shoot different brands and weights to see which one(s) your shotgun prefers.
Depending on what it is choked, yes. Have a gunsmith examine it.
No
Not recommended.
1. It can, but, it is not advised. 2. It is stated by Smith and Wesson that the model 14-3, which is the third change of the model 14 can safely shoot plus P ammunition.
Needs to be examined by a gunsmith.
You need to find a firearms instructor.
.32 rimfire Smith and Wesson model 2 1/2
NO
Not recommended.
You can, but, you should not. The frame is not rated for +P
Simply put, no.