The traditional title for the heir apparent to the British throne is Prince of Wales. However, this title is not automatic and is bestowed by the monarch. In Prince William's case, his father, King Charles III, has not yet conferred this title upon him.
It is possible that Prince William may receive the title of Prince of Wales in the future, but it is also possible that he may not. The decision is ultimately up to the King.
As for the surname Windsor, this is the royal family's official surname, but it is not always used. The royal family often uses other surnames, such as Mountbatten-Windsor or simply Mountbatten, depending on the context.
