Quite a few of us. Both of my nieces, their friends in the dreams, my brother-in-law and more recently my sister. I think there are 12 of us all together.
It depends on the person. In our dreams there are a class of people known as Hunters and Huntresses. We protect people from dangers in the world: thieves, monsters, etc. Most Hunters and Huntresses unlock their semblance while they are undergoing their training as teenagers. Some people, though, just unlock them, usually by necessity, though sometimes at complete random.
No, I can't control the bad luck. As I said, sometimes it just happens. Pretty handy to have in a fight, but any other time significantly less so. Do I have any luck with it here? Interesting choice of words, but I guess maybe so? My biggest concern is somehow hurting my family because of it, but so far that hasn't happened.
Its pronounced "crow", like the bird. Which all things considered is very fitting.