Thank you for going into such good detail; it's so helpful to be able to visualize a realistic, long-term goal concerning this.We have goshawk, red-tailed kites, buzzards and kestrels; possibly others but those 4 I've seen.
Numbers matter, but not because they're food. There is an element of safety in numbers. The more on lookout, the better the warning system.
When the 'predator detected' kind of alarm call goes out, my free ranging flock forms a tight group, typically 4 or so mature roos at the edges and 10+ hens in the middle.
This presents any predator with a significantly greater risk than, say, 3 hens with or without a cockerel. Hawks do not want to risk injury from a fight with a roo - their lives depend on being in full health, with perfect vision for example, so getting a meal takes second place to preserving their faculties. So confident adult roos are enemies that hawks avoid. There are easier meals out there, and the hawk moves on to find them instead. I have found that multiple roos are an excellent defence against terrestrial predators too, though we don't have to worry about anything bigger than dogs and foxes here.
On hearing the alarm broodies and chicks (with or without a roo escort), who are usually apart from the adult flock, typically scatter in all directions to separate cover, and usually they are close to cover so disappear before the hawk arrives. Cover for a chicken means hedges, bushes and shrubs, not trees; ground level, relatively dense, and ill-lit. An isolated hen may dash for cover and/or drop flat and keep completely still.
If the attack was not detected in advance, and a commotion is caused by the strike, everybody runs full pelt, the hens for cover, the roos (or broody, if it's one of her chicks screaming) to the source of the noise, where they go into attack. I once had to rescue a kestrel from a broody.
So yes, your chickens will learn how to deal with your predators through experience. It is hard at first, but those with good instincts survive and teach the young (especially if you hatch with broodies) and chicks learn very quickly, so it only needs a couple of years for success. I have not definitely lost a bird to a predator since 2020 (a few have disappeared in those 5 years, but with no pile of feathers anywhere, and no flock trauma from witnessing such a thing, I deduce they were just lost in the case of chicks, and went off somewhere quiet to die of natural causes in the case of adults).
Is it ever a problem to have that many roosters together in a flock? Some people say you can only have one rooster or they will kill each other, and other people say that you can have any number if you have enough space for them.
We are currently in the process of thinning our woods and making space for sunlight to penetrate--sounds like that will be a good thing for the chickens since it will allow thicker, brushier growth close to the ground.