Every car can be different depending on how the Master cylinder and the anti lock brake valves work. I had a truck and a car that ate rear brakes and not front. Of course I also have had the opposite. I have a corvette with 75K miles and I changed the brakes and rotors just because of age. Neither pair where at minimums. And I drive it hard on the 3 set of tires. So I am focusing on the wear part of your statement. Replace them. As far as rusting, can't believe the wear area has anything but surface rust until you apply the brakes first time in the day. So coating is the hub area only and that is cosmetics only, no???