The M1014 is the Benelli M4 Tactical. It is available only in semi auto. The Benelli M3 is the closest thing you'd find - it has the "dual action" feature, to where it could operate either in semi auto or pump action mode (in a similar manner to the Franchi SPAS 12). Additionally, Benelli has a whole line of pump action shotguns (the Nova series) which will share some commonality with the M1/M2/M3/M4 shotguns.
When properly maintained and operated, they are as safe as any shotgun. They have a good reputation as a reliable firearm.
No, these forearms function differently. One (742) is stationary and has a steel liner protecting the inside of the barrel channel from any escaping gasses. The 760 forearm slides onto the action bars and is made to function in the same manner that pump action shotguns (like the 870) perform. These two forearms are NOT interchangeable.
Contact Marlin customer service thru their website. I have no listing for a 30-30 pump action Marlin in my references. There are other calibers, but no 30-30.
Not sure what the question is, be more specific, each gun has its own magazines, and spring guns suck if not bolt action rifles or shotguns.
The Superposed is an over/under. Check the BPS section on Browning's site for pump shotguns.
No
Yes
You did not list any "following". Hardly fair to make us guess what they were. By the way, the image shown above is an example of a pump action firearm. The forend is "pumped" back and forward to eject a fired shell, and load a new one.
Check the price of a new pump of similar quality and the same gauge in any sporting goods store and figure your used gun is worth from 1/2 to 3/4 as much. Most catalog store pump shotguns will bring from $75 to $150 at an auction.
For open carry and hunting, federal law alows you to have any type of rifle which is not a machine gun or a short barrelled rifle. That means any caliber up through .50 cal in any action type including break action, bolt action, pump action, lever action, or semi-auto. Full-auto (machine guns) are highly restricted.
All Browning B-2000 shotguns were Belgium manufacture but assembled in Portugal.
Browning Arms Co. did not make or import any pump action shotguns in the 1950's. This gun was made by another manufacturer and could possibly say "Brownings Patent" on the gun. John Browning invented dozens of guns that other companies made. This may be what is throwing you off. Check the gun again and find the manufacturers name. It is likely a store brand such as Sears or Western Field.