The hens are much smaller than the drakes, so you won't have three huge ducks wandering around - just one huge drake and 2 small hens.
They're smaller than adult cochin hens. Quieter, too. Females will only whistle and maybe hiss a little, but can make a dry sounding quack very rarely when startled. This is very unusual. They are the quietest animals on my farm, except for my rabbits.
He is likely not aggressive, but is instead likely terrified and stressed out. If he is tame and was raised by people, he may see YOU as his flock and is trying to dominate you. I have a brooder raised drake that bonded to me, that is guilty of this behavior. He bites (not as hard as you describe) and can be a snot sometimes, but is generally a very sweet boy. But, he doesn't understand why I 'challenge' him all the time.
As for flying, they can do so quite well if they develop their wing muscles. If I were you, I'd temporarily pinion him by trimming the flight feathers on ONE of his wings, to make sure he stays grounded. He could then free range if you desired, as long as he has an area to get out of wind/rain and knows where food/water is.
Free ranging is the only way I'll ever raise any poultry, especially muscovies.
Congrats on the 'scovies. I'm sure soon enough you'll have a bunch of them. I wanted a trio to begin with. I now have enough that I haven't counted in a while. I would bet it's over 20, though.