It depends on the dogs and on your own preferences.
Some dogs are picky about which parts of the chicken they eat. You have to learn this by experience with your dog.
Many dogs are happy to eat every bit of the chicken, in which case they can get everything you don't want to keep for the people. Yes that includes feet, innards, heads, wings, bones, and usually a few feathers if they are attached to something else.
You can freeze parts for the dogs by putting them in bags and sticking them in the freezer. Think about what amount you want to have in each package so it's convenient. For example, one meal for one dog in one package, or one week's worth that you then thaw in the fridge and hand out over however many days.
There is no need to age the parts for the dog.
