The salutation would be: "Dear Sir or Madam" - hopefully their response will indicate their gender. Perhaps you could call their office and ask for "JR Smith," and the person answering the phone will respond "Mr./Ms. Smith is not in right now ..." and answer that question for you!
Why would it not be okay? Maybe it's not information you would share with everyone in the world but I wouldn't let it bother you. Some people out there will judge you no matter what - just remember that stuff (being judged by people) is going to happen but it's really not about YOU but about...
Steam or microwave them (or stir frying is quick) - boiling will suck out all the good stuff and leave you with something tasteless. I like my veggies to still have some crunch to them!
Too soon to tell - depends on what happens within the royal family, who has children, who does not, if someone abdicates the throne, dies young, etc. As it stands right now, it looks like she would be the granddaughter (or possibly great-granddaughter) of Elizabeth II. From there it's anyone's...