Sorry, can't help you with the medical information, but I can tell you the ships aren't registered in the US-- I think they're reg. in the Bahamas.
We've cruised DCL twice, and are going a third time, but with the price and now three kiddies-- it's getting to be out of our league. There are some good sites that focus specifically on Disney- don't want to post sites because I don't post here often and honestly don't remember the rules on that.
Hope you get your info