Leghorns are a single combed breed, the browns and whites and all other of the more rare colors, too. Leghorns aren't called "single combs"-all the birds you have listed other than your "Araucanas" are single combed breeds. That's what was confusing us.
No chicken goes by the term "single comb" or no one will understand which one you're talking about. There are single comb Rhode Island Reds and rose combed Rhode Island Reds, but they're all called Rhode Island Reds, so you need to call yours Brown Leghorns.
They can lay really huge eggs, for sure. Leghorns are the white egglayers that supply the jumbo eggs on grocery store shelves.