I have some questions for all those with a more developed knowledge of titular protocol. Everyone's been throwing Princess Kate around, but I started thinking about it and just didn't think it played out like that. Wanted some answers.

1. What is Catherine Middleton's last name now? Windsor? Wales?
2. Is she a Princess? Based on my own limited knowledge of how it works she would be Duchess of Cambridge as Prince William's prince doesn't come from a title like Prince of Wales but from his blood relation to the Queen. So they are Prince William, Duke of York and Duchess Catherine of York? She wouldn't become a princess until Charles becomes king and William becomes The Prince of Wales, right?
3. If they have a son before Charles becomes king would he use the Prince's second title as Earl of Strathearn or does he just use the royal Prince title?

Any info is appreciated.