I would get the aggressive tendency towards you in check, NOT acceptable. I have had a lot of 'scovie drakes i don't care what season it is there better be no issues with me.
As for the rest, depends a lot on the birds, the temps and so forth... usually you'll see down plucked out when there serious but of coarse molting is a possibility due to spring arriving. How many eggs they sit on will vary, my last lady sat on 5 eggs through the end of a winter, it resulted in 4 eggs hatching, so i have 4 almost 3wk old babies right now.
If your not around you may not see the breeding taking place, it would be unlikely that it wouldn't be at some time or another... i cannot honestly say if i recall my duck who just had the brood breeding and i am here a lot but it's not this long courtship so can be missed.
Up till the babies hatching which is about 32-35 days, i leave the mama duck alone, i don't do anything different, she'll come off the nest to forage, eat.. join the flock for a bit etc.. as hatching draws closer she won't as often and almost not at when hatching is about to begin.
When babies are due to hatch, i am prepared to block her off giving her access to feed/water that is compatible with young and usually in non winter times leave it at that. Since i own drakes, i feel it's important she feels and is secure with new hatchlings so the fencing off is important, sadly some drakes can kill ducklings, now i don't think mine would but why take a chance?
Unfortunately, this time 'round because of winter i had to move my duck & her brood to be able to use a heatlamp our temps were not of the state for her to maintain their warmth or even her own, but generally i don't move them.
Now some will down size nests, especially for 1st timers to increase the odds, i have not done this... and my birds are not first timers anymore either.
Good luck! May i also recommend Storey's guide to ducks, there is info on breeding!