No expert here at all. Butchered my first one last week. I too looked all over for information on how to, feeding to finish, etc... My hen finished at 23lbs.
We finished with a 25% corn to pellet the last several weeks. I didn't seperate or put it on fast for last 24hrs as some suggest-mostly because she was with two others. The only drawback becides feces is the gizzard was full. Just need to anticipate that if you plan on eating it.
I employed my Father-in-law(FIL) and didn't do anything elaborate...no additional expenses. I brought her out of the pen, layed her down on the earth. My FIL held her head over a log and decapitated her with a hatchet.
From there, she bled out for a minute and I carried her over to the hot batch. Temp was 150 F. Sloshed her around for 45 seconds or so. I was told that when the skin on the legs/ankles slough off with a bit of friction, they're ready. That's the method we employed and the feathers came off SOOOOO easy.
Afterwards, cut a hole around the anus and pull out all the goodies. Rinse & clease the cavity. Try not to puncture intestines or any entrails.
Rinsed her off and then put her in a cooler with 20lbs of ice and covered her with water. We dumped 1.5 cups of kosher salt granules and left her over night. The salt water pulled the blood out and left us with a beautiful succulent bird in the am.
Its really easy.