I'm going to take a stab at the first question. First, think about the size of the top of a typical old wood or coal stove. It was very limited on room and there were no microwaves back then. Next, there are a lot of uses for a small skillet, melting butter, making a sauce, or just warming up a serving of something already cooked. If you had a couple of skillets on the stove and needed something heated to add to one of your dishes then there was room for a small skillet to do the chore. Even now, I use a small skillet for doing this sometime, although the microwave usually does it.