I've only had chickens for a year, and they were raised on pine chips. We now put straw in their coops, but sometimes we run out and have to use the chips. I've never had a problem, though. I'm not sure about other kinds of chips.
Just so you know, you might want to hold onto them for a while. Hens crow too, and until you're sure they aren't going to lay eggs, it's best to keep them around. I understand that you can't have roosters, but we thought one of our hens was a rooster, and so far, she's laid almost every day...
I've never had this problem, but my chickens didn't lay in the nest box. Instead they built their own nest in the bedding. Have you tried putting a wooden egg in the nest?
I think adding a wooden egg is supposed to help, but to be honest, I've never had this problem. Do you put them away at night? Mine didn't use the nest box we provided and instead have built a nest that they all share in the corner... That's not really the same thing, though, is it? Hm, any...
I'm getting chicks in early september and they'll go into the coop when it gets cold here. I think that if your coop is insulated and you have chickens that can huddle together for warmth they should be fine, especially if you put a heat lamp in your coop.