No, you can not shoot anything but 12 gauge shotgun shells through a 12 gauge shotgun. Never use any ammunition other than what the firearm was designed for.
Unlikely more than 125 or so
Yes. Some shot types are more lethal than others, but any shotgun can be lethal.
the 10 is alot stronger and has more ranger but 12 is better for hunting.unless your hunting very big game
Yes. The Mossberg 500A1 is a .12 gauge shotgun.
No more than 100 USD.
Seldom more than 100 USD in excellent condition.
Yes, a 12 gauge shotgun is considered a firearm.
A bolt action shotgun in 12 gauge.
Overall, the .12 gauge shotgun is a substantially more powerful firearm.
All else being equal, yes.
a 12 gauge shotgun can shoot about 30 yards accuracy