I am sure a scovie can hatch chicks, but I would be more worried about if you leave them with her that she will encourage them to follow her into water. Or if they don't and she returns to them all wet etc she can kill them just because they get wet from mommy who is supposed to keep them warm. Ducklings have a protective layer of down who keeps out a light coat of water so they can huddle under a wet mom without freezing, but chicks would get cold imidately.
Ducklings like humidity but chicks really don't do well with it.
As for tameness, I got my drake as a untouched 7 month old who was intended for the local asiatic market(I don't like white ducks so what better place to look for the blackest ducks possible then at a breeder who breeds for people who don't like white feathered fowl). Anyhow, he was the biggest spook but he calmed down within 2 months and even though I cannot catch him unless he is cornered he will still stand by my feet and wag his tail at me, hissing and bobbing his head as a greeting every time I enter the enclosure.
If you get him he will just kinda hang there with the "dang, she got me" face, no scratching or anything.
I did have a Moulard(PekinXScovie) drake once back in germany, and nothing will turn a 8 yr old off of ducks faster then a large, muscovy sized drake with the most hysterical nature and Muscovy claws....... I still have the scars up and down my arms and stomach from that hysterical beast.....
Took me 9 yrs to want to give ducks a try again(tried mallard derrived ones and their spooky nature just wasn't my thing) and then I got 12 scovie ducklings and a 7 month old black pair and since then I never want to be without scovies again!
Anna