You say that there are feathers in the coop and pen area. This is the time of year when many birds molt. This could explain why some of your older birds aren't laying. How old are your young birds?
If you have too many roosters, they can stress hens out a lot, which might cause them to not lay. However, I don't think that they are the only reason for your hens not laying. Is it possible that your hens are hiding their eggs? The daylight hours are also decreasing, which might prevent laying.