Ok if you look at the link of the clamshell action that I included you will see that they have an extra web of metal that goes from the water table to the standing breech/actionface and wraps up around the barrels. The reinforced action simply has extra metal that goes from the sides of the water table to the standing breech. Thus it refers to extra metal on the side of the action and not to the barrels. The Heym above has a reinfoced action.

Clips were orginally designed to help with the rotational force of firing a sxs. Personally I like the look of them but I agree on the sharp part and wouldn't care for them on a DG gun that I might have to be forced to reload very quickly. Of course i wouldn't want a huge rib extension like you need for a greener crossbolt on a DG gun either. Now in all fairness I've never hunted anything more dangerous than bears so most of this could be totally wrong opion, but it is my opinion.

In the pic I had labeled earlier. The lumps would be the 2 large protrusions from the bottom of the barrels in which the bites/underbites are in.

You have monoblock correct. However there are many guns made with monoblocks. A lot of them are cheaper guns because it is easier to use monoblocks during manufactureing but there are better guns with them as well.

Bill