Depends entirely on your intended end use.
2
Depends on what it is choked.
The 410 is a shotgun round. Slug loads are available and have been made for decades.
MUST be examined by a good gunsmith
Needs to be inspected by a good gunsmith.
Yes, for sure.
With a slug, maybe. You had better be able to put the slug in the eye at 50 yards.
The Short answer is yes. Even in a 410 gauge shotgun with a full choke. Remember that a "410" is 41 caliber or .41 inches in diameter. oo buckshot is only about .32 inches in diameter. The same is true for shooting slugs in a shotgun. There is no safety issue involved. You will notice that there is no warning on the packaging of the ammunition. In our litigious times you can be sure that if there was a problem there would be a warning printed on the box.
The Stevens 59A can shoot all size loads from #12 to slug. So in short, yes.
it is shotgun because the size of rifle is different than shotgun.
You can use nothing but 410 shells in a 410 shotgun.
The 410 Shotgun is really .410 Caliber. Unlike all other sizes of shotgun, (10,12,16,20,28gauge), the 410 is measured in caliber. I believe it works out to something like 36 gauge. So the 410 shotgun is .41 Caliber