You can apply some Pick-No-More or Blue Kote to the skin, this may help lessen the redness.
There are many reasons for pecking, nutritional/vitamin deficiencies, overcrowding, boredom, etc.
You may want to increase protein intake, sometimes feather picking is lack of protein.
Having enough roosting space at night and a large run or free range during the day can help with overcrowding issues. Give them some things to do if they are kept in a run, add perches to the run, hang fruit/veggies for them to pick at, dump in some leaves or weeds from the garden for them to hunt and scratch through.
Sometimes it is the "Alpha Hen" that does the picking, but when roosting, the lower in pecking order girls can get in on the action as well, their "victim" is beside them in the dark, so they take advantage. If you can figure out who is doing the picking, then isolate/remove them for a few days away from the flock. Then put them back in, sometimes this may help disrupt the bad habit, but not always.
http://www.the-chicken-chick.com/2013/03/chicken-feather-loss-cannibalism-causes.html