They all get tail curls sans Muscovies, but sometimes they can get pulled out. My boys got their tail curls between 16-20 weeks so I bet yours should be getting them soon they are just a bit young.
Very much boys! They have the drake curl and all to go with the raspy quack. Please keep a very close eye on your boys as they can seriously injure or kill your chickens while trying to mate them. Ducks and chickens are very different in anatomy and it is a big risk to your chickens.