Is Burke's Peerage the same thing as Burke's Peerage and Gentry?

A last name Also used as a word to describe an idiot (in Australia).

Not necessarily. Density is mass divided by volume. Many different things could have the same density.

If Fall is the same thing as Summer, and there are four seasons, then that would correspond to 7 days of the week, meaning it would actually be closer to Saturday.

Yes, "how do you do?" is a more formal way of saying "how are you?" It is more or less archaic. However, "How do you do" is never responded to literally, by telling the greeter how you are.

No, they are two totally different people. They don't even look alike, except that they are both black.