My flock is an absolute matriarchal society, lol... Lady Grey is technically the main Alpha, but she has several co-Alphas she has accepted as equals... they keep the peace, sound alert for danger, lead the flock in curiosity, and wait til everyone goes up for the night before going in themselves...
Ducks can reach maturity as early as 5 months up to 9 months, I have even heard of some at 4 1/2 months... a lot of factors depend on breeds and whether they are hatchery stock or breeder sourced...
Most ducks start head bobbing, flattening out with heads stretched out or do the crazy ducker dance, run in circles with their heads stretched out and level right before they are getting ready to lay... but not all do...
Some will lay in nests, some will hide their eggs and some will just drop their eggs wherever they're at... in mud, pools, etc... getting clean eggs from ducks can be much more challenging than from chickens, lol...
Most will at least dig out a shallow hole to leave their eggs in, this is not a sign of broodiness, just natural instinct to hide/protect their eggs...
I have not had a big issue with bossy ducks, but plenty of space is key... as long as each group has space to call their own, avoid others they don't get along with as well, then they generally have little issues...
Broodys... how to handle them is completely dependent on the trust bond they have with you... some of mine have complete trust and I can move them, handle their eggs, handle their ducklings and do anything I need with or around them... some are more skittish and prefer me to keep my distance... others are super protective and reaching close is at risk of finger loss, lol... and a couple just let me know that they got this and don't need any interference... luckily, most of mine choose good nesting spots, ones that don't I secure if possible, and move if not... a simple bottomless box with a swing down door hatch placed over them makes an easy broody protection cover...
I have had pairs of co-broodys sit and raise their clutches together, one time a trio, and even once had 2 broodys hatch each of their clutches a week apart who joined together and raised their sets together...
Some can raise their broods just fine within the flock, some prefer a bit of separation at first, until the babies are a bit bigger and tougher... some broody groups can be around each other, some need to be completely kept apart... each one will let you know what they will or will not tolerate...
I keep many feed bowls scattered around, causes less drama and food competition, and each group can eat together that wants to... I give layer feed and also flock raiser as free choice... some prefer one over the other, plus I usually have many ages and lots of drakes... oyster shell always available free choice no matter if they're eating layer or flock raiser... some need more calcium than others and will add more to their diet when needed... a couple tend to have calcium issues well into their laying cycle, so they get calcium gluconate or calcium citrate as needed...