Welcome to 'scovies!
Yeah, i probably wouldn't, i have 2 mature drakes, i do not let them near the chickens, yes some people have no issues but frankly, i don't want to find out the hard way that i do.
Go for as many ducks as you can, the two will fight expect it, also be prepared they may need to be separated at night, i stall my one drake the other stays out with the ducks(he's gentle) i have 9 ducks for them and am adding 2 more, plus have another nest so i may keep some females from that(if their are any lol)
Storey's guide to ducks if i recall right recommends Muscovy do best with 5 ducks per, but i'll double check as soon as my kobo updates
Alright, he states 6-10 but that is for peak breeding performance..
Differences? well, scovies girls fly and well, so be aware of that, they also like to roost i have a shelf in barn for them and some boards set outside for this purpose. Drakes rarely get off the ground past 1yo their bulk weighs them down.
If you go cold, i would suggest Vaseline on the facial flesh this reduces the risk of frostbite. While 'scovies do have an underdeveloped oil gland so in other words not as waterproofed as mallard derived they still like to swim, and need to for feather health. Kiddy pools will do.
As well because they are not mallard derived if they mate with one, all young will be mules(ie; sterile)
I think that about covers it lol There good, hardy, ducks, VERY broody and well documented for their fly eating skills..