Look through this. It’s at the start of the meat bird section and has a lot of how-to information in it. If you decide to process some yourself you can get all you need from these articles and threads. As you look through it you will see there are many different ways to do anything in the process.
Many people are just not equipped to do it. If you are one of those admit it to yourself. You are not alone. It’s better to not try than to flinch or close your eyes at the wrong time and just injure the chicken instead of getting a clean kill or even worse in my opinion, injuring yourself.
You still have options. Find someone to process them for you. Maybe find someone that will help you the first time so you can get through the process. Or just give them away so someone else can get the benefit from them.
I don’t have any links handy but because they are that old they do need to be cooked differently. The older a chicken gets the more flavor and texture they have. If you try to fry or grill a chicken that old you probably won’t be able to eat it. The secret is cooking them slowly and with moisture. Baking or stewing are two excellent way to cook an older chicken.
When I cook a two or three year old hen, and I do cook them, one way is to cut her into serving pieces, coat those pieces with herbs like oregano and basil, put her in a baking pot that seals pretty well, add a tablespoon of water, and bake her in the oven for maybe three hours at 250 degrees. 250, not 325. I defy anyone to call that meat tough.