I have this one with the light sensor. You can also just have it open and close at a certain time. I love it!!
http://www.chickendoors.com/products.htm
I do not have a rooster . I haven't noticed any pecking - this spot , I know it's hard to tell in the photo, is like a swollen bulbous area. I've had pecking issues before and this doesn't look the same on the bare area.
So glad to read this is normal! I thought I might have a rooster since mine aren't laying yet. We are in the same situation in our neighborhood. I think I probably caused it with the treats.
I'm wondering how to train them too. I just put one in the coop and showed them several times . I have not seen them use it - not sure how to tell if they are.