The number of eggs sounds good to me. Their cycle is supposed to be about 25 hours. A hen should lay a little later each day til she lays late in the day, then she should skip a day and start over in the morning, as they should not lay at night. Obviously, they are individuals, and lots of things can affect laying. Also, they will likely lay less in winter, related to shorter days, and they may slow down in hot weather as well. They will usually quit for a while when they molt, and if one goes broody she will stop laying.
The missing feathers on their back ends is a bit more bothersome, and there are a lot of possible causes. It should not be from molting unless you see a lot of feather shafts coming in. Rooster damage is usually most obvious on the top of their backs -- in the middle of their back, kind of where a waist would be, not on their butt. Unless he was pulling their butt feathers, of course.
Probably the most likely causes of bare butts are others picking feathers, and lice / mites. First thing I'd do is check carefully, at night with help if possible, for lice / mites (see link below.) Feather picking could be because they need more protein or because they were feeling stressed, from overcrowding or any of a number of things. Since they're already doing better, I wonder if they were too crowded where they were, or are just more comfortable now. But they could still have some lice or mites; they are not uncommon, they are carried by wild birds and can just be dropped onto them. I sprinkle a little Sevin on the coop litter and in their nests now and then.
http://ohioline.osu.edu/vme-fact/0018.html
