Unless specifically prohibited by the owner's manual, yes
yes i have done it
Can't be answered without knowing what it is choked.
Contact Stevens Customer Service through their website
to test it take apart a 410 slug and see if it fits through
Depends on what it is choked.
Yes
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.
The Stevens 59A can shoot all size loads from #12 to slug. So in short, yes.
A properly loaded shotgun shell slug load, yes.
currently all they offer is a 12 ga bolt gun
Any non rifled slug. However for best perfomance you want a "saboted" slug.
No