@Aquatic_blue - there are low cost options you can implement. So, don’t feel too stressed.
1. Since you live in a dry environment that doesn’t get frightfully cold this is a positive. In fact, enviable to those of us that went through the horribly wet and icky fall/winter/spring of ‘18-19. Your girls hopefully have a decent run area they can access.
2. The pre-fabs aren’t made so great, but others have modified theirs with a few things that help, but for you, protecting the coop from sun/rain can help. A piece of scrap OSB/plywood/metal or plastic roof panel can shield it from some environmental damage. Think about each Structure problem as it’s own issue, and decide if it can be fixed/improved within reason. As each gets solved you’ll feel more accomplished while staying within your means.
3. Pecking order -it happens, and can include bloody combs. But, the other thing that can cause this is not enough protein. If you are feeding a 16% feed you should not be giving them any treats bc this dilutes their protein intake. Well, canned or cooked meat would help, but generally $$. And, yes they will eat meat...even chicken. So, you can switch to an all-flock feed, usually at 18-20% protein, but you need to supply calcium for the layers -usually in the form of oyster shell. Or, you can look for a layer feed that is higher than 16%. Some people supplement with dry cat food for extra protein. If you do this, crush it or add some water to soften. Do not replace all their food with this...it is not meant as the sole ration for poultry and is not designed for that, but it is an inexpensive way to supplement protein on a small scale.
Overall, feather picking can be boredom, so a bigger run will help. Can be lack of protein and feathers are mostly protein and they will eat feathers. Can be pecking order. But, you can address the space and protein requirements as a chicken keeper.
Definitely plan for a bigger/better coop when you can. With this coop, don’t add any more chickens. Many keepers do not have huge coops, but have a peaceful flock. My coop would be undersized according to many on here, but my flock is generally peaceful. I do feed a 20% all-flock bc I have males in the flock and some M and F are very large breeds. I have a large run for the flock, and visual distractions/interruptions which helps with pecking order.
good luck!