"Note that villagers need to be in a well’s or box’s range, and not the other way around." But what are the range of the food box and well? It doesn't show like the villager's range.
They show, just pretty large (unchangeable range).
Try zooming out (scroll wheel) to see their ranges, when interacting with them!
I read somewhere that each workstation can be worked by three natives at once, is it true? That same comment also said putting 6 natives near each workstation maximises efficiency. The native huts have enough space for two people. So I need three huts per workstation.
Uncertain on actual efficiency, but yeah, while 3 can likely work "at once" at the same station, it's not like they're at it 24/7, there's some randomness as well.
Additionally native huts, if you do space the beds apart nicely, can actually have much more! Alternatively, think of upgrading the native hut to a wooden or stone house, for some more space inside.
The problem is, as you mentioned in your guide, natives will enter a hut and if they find the beds occupied they will just stand there and won't go to another hut. Is sleeping essential for them? I read that they will lose "moral" if not getting sleep. What does "moral" do anyway? Do they rebel? What happens then? Or will they be just grumpy and beat up their coworkers?
If their morale reaches too low, they will "rebel" in the form of attacking someone when their lust is too high (never had it occur otherwise I believe, but then again, that was pretty much always the reason for morale loss on my end)
And yes, they do loose morale when they don't have a bed and are not on guard job. (Some exceptions can be made, ex.: animals, special npcs and such)
Also, where can I get clay?
Dig with a shovel in the swamps (or where you can find trash, those small puddles that slow you down)
Chicken can be bred? I've put male and female chicken in the coop, cage and breeding pen. Noting happens. Do they need natives working on them?
Don't think they can actually be bred, but if you put them in a chicken coop (non-males, up to 3) they lay eggs every morning. the "chicken?" has a chance to lay golden eggs!