I would pick up some fence posts and some welded wire as I could afford it and put up some fencing around the coop so they can get out more, those type of coop situations are mentally unhealthy on chickens, and they end up pecking each other, chickens need way more room behaviorally than what is...
I see your point, more than likely they would end up in the woods, if I had your setup I would probably set up extras runs as I could and eventually rotate areas since you have so much yard, and I might start planting trees or shrubs so your chickens can have some cover and shade.
I've kept chickens for a long time, I've only had one killed by hawks, it was a muscovy hen that it couldn't pick up because it crawled under a nearby truck. Cover is the best protection from aerial predators. I've lost a couple to Fox and coyotes, but those were at night or early morning. It...
Best thing is let them out in the evening, they will want to return to the coop by dusk, you can also just let them out whenever you are there or have time, some time is better than no time.
And you will probably open the door the first time and they won't go out, and they won't go far until...
It does sound more like a protein deficiency more than boredom, it starts with random feather picking and eating then quickly escalates, your hens are still quite young, they are growing and maturing as well as laying, it can quickly deplete them, feral chickens would seek out protein, yours are...
Scratch can be good for boredom, throw it in the run to give them stuff to scratch for, but you're right it can lower protein, I like keeping my hens on a grower or an all flock because it has higher protein, with a free choice oyster shells, I also give mine some black oil sunflower seeds, I...
Separate out the hen until she heals, a wire dog crate will work, then you need to figure out why they are doing it, how old are they, what is the size of your coop, what are you feeding them, how big is their run, what's your setup like, it's not normal for them to start pecking someone for no...