Had a hawk go for our chickens the first time we started raising them. Probably almost lost a few, but our rooster jumped up and kicked the hawk out of the way, saving the hens. He got nicked on his comb from it, but no real damage. This is a good article, with good info on chicken safety.
Nice overview of winter predators.
A predator apron is typically more than 6 inches away from the coop wall; 12-18 inches seems to be the standard recommendation.