It's okay, i know.. i often just hatch my own here.. i am drake farm that is how i am known lol I had a clutch of 9 in 2012 and i got 1 duck! anyways, quarantine times vary by person... i got a slightly older duck last fall(she was 5ish mths) i did 3wks... usually when ducks are well cared for they are not as much of a risk as chickens but depends, always depends. Reliable sources are very important.
As for ducklings? i usually if a mama is not there wait till at least 8wks but the older the better, you can allow them to be within the flock with a corral but older ducks can be rough on babies/young and some drakes can kill ducklings, a caution worthwhile to state.
Ducks do not have as rough as a pecking order as chickens, but many times i will separate young at night for even longer as adults can be bratty in the coops compared to the more roomy outside.