Extra-toed cats aren't a breed. Polydactyly is a harmless genetic variation, and most of these cats are ordinary domestic shorthairs or longhairs with mitten-like front paws. The trait is dominant, so one affected parent can pass it on. It's most common along the Atlantic coast, where ship cats were prized as mousers, and the Hemingway nickname comes from the six-toed cat a ship's captain gave Ernest Hemingway.
Personality has nothing to do with the toes, so a cat might be a lap-sitter, a chatterbox or a shy one who takes weeks to settle in. What does change is claw care: extra claws can curl into the paw pads, so plan on regular trims. In a warm, humid city like NOLA, coat length matters more than toe count, since a longhair needs brushing through the muggy months.