I don't do quail the same as chickens. For quail, I tried breaking their necks, but wasn't very good at it, so someone showed me how to crush the heads and that worked out fine for me, but it seems harsh......harsh, but effective. I then just sit down comfortably and start removing the feathers, carefully. Then remove head, feet and make the same cuts as I would for a chicken, but only insert one finger and begin removing the guts and organ meats. The tricky part is the esophagas, but if you use a finger to push at the neck, while using another to grab from below, its possible.
As to processing chickens, I have a nail at about my chin level with a string hanging in 2 strands, which I use to tightly tie the feet. Then I slit the throat.....go deep with the cut, so you don't have a long wait for the bleed. I have a small barrow under the bird to catch the blood and feathers. The bird will flap and fight after the cut for a while, which helps them bleed. When thats over I start with the wings and then go to the feet and work my way to the neck. Some areas are more sensitive than others for skin tears, but I have learned how to pluck without causing skin tears most of the time. Its a directional thing. The areas that will tear.....when you get to the corresponding area on the other side, just pluck in a different direction and see if it works better and remember how you did it. The area just above the thighs are difficult and right under the wings and sometimes the breast if you don't have the tech down perfect. Use small swift movements. Try a small piece at a time, until you have it. And don't let the bird cool off. Pluck when its still warm. Okay, I then use a pruning shears to cut or break the neck and remove the head. Then I cut off a single foot and that opens the vent area. I then pluck the vent area and make my incision to remove the guts and organ meats and when I have it all cleaned out I remove the remaining foot and go to the sink for a wash-up.