Muscovy are not mallard derived ducks so they do not get drake curls that is a mallard drake feathering.
As for the voices those are typical juvenile muscovy sounds .. i can try to see if i can get adult voices today but that is not easy... size is where you will find the difference long...
Not in my experience.. vocals in scovies come much later. I have some 6wk olds no voice differences right now.. all size. I have some other babies(they are my avatar) a bit older again, all size.. i am not hearing anything differing yet but i can sure tell who is who...
White drake...