She could be HRHPrincess William, but she seems to go just by the DUCHESS OF CAMBRIDGE.
He will still be Prince William.
If the father (Prince) does not hold another title, his children will be Prince or Princess. The off spring of that Prince will also be a Prince, but not so with the Princess - especially if she marries.
If he dies without children, Kate will be the dowager (whatever her former title was). And then Harry and his line will succeed to the throne. However, if William dies before he marries Kate, then Kate gets no title at all.
Prince William has not lost his title as prince. The duke of york still retains his title as prince Andrew however it is common for the queen to give other titles to royal members when they marry. When William married Catherine she automatically receives the title princess William but they will be officially known as the duke and duchess of Cambridge. Also a duke is higher than a prince.
She did, she bestowed the title of Prince on him when he was born.
No. That title has been given to his father, Prince Charles.
The same thing that happened to Elizabeth- she'll be in line to be Queen. She'll knock Harry from being 3rd in line to the throne. And then when she marries, her husband will take a title such as Duke of Edinburgh (a guy who marries into the family can't take a higher title than his wife, who is of royal blood. Therefore, he couldn't be King.).
Prince William is now the Duke of Cambridge. He will not become the Prince of Wales until his father Prince Charles, the current Prince of Wales, becomes King. Even then, the title of Prince of Wales does not begin automatically. Prince William must have an investiture which bestows the title of Prince of Wales upon him. This answer was re-written by DieselEstate on 20th April 2012
No. That title has been given to his father, Prince Charles.
Harry's wife will become a princess and will take the major title of her husband, depending on what that is at the time For example, when Kate married William, she became a princess, but took on the title of 'Duchess of Cambridge' because the title of 'Duke of Cambridge' out-ranks your bog standard prince title. When Charles and Diana married, Diana took the title of 'Princess of Wales' because Charles was the Prince of Wales, which was a much bigger deal than just your normal 'run of the mill' prince.
Because the Queen appointed this title to him
Neither, once a prince he can only be king. Actually, a duke is higher in Nobility Rank than a Prince. A prince's title does not change because he marries, however, once he marries, he is usually awarded a dukedom for his parents (King/Queen). As the ruler of this dukedom, he then becomes a duke. An Earl refers to chieftains set to rule a territory in a king's stead.