I've always done quarters because they are readily avaliable to me, and I have not been able to find someone to order in bulk for me. (Since the freezer is currently PACKED I haven't been looking though)
I've never had an issue with the quarters, they have less bone than backs, and I had to take the skin off for my Boxer puppy at first, but my Corgi did wonderful, skin and all.
The amount you feed is based off of the ideal adult body weight of your dog. My Corgi is 20lbs, and eats 1/2 lb per day split into two meals. My Boxer is a puppy but we expect her to be about 60 lbs, and she currently eats about a pound and a half, split into three or four meals because shes still a puppy, eating an adult amount of food per day.
I buy the quarters at wal mart in 10lb bags for about $6.