Our setup goes like this:
Chickens in crates
Six kill cones on a steel stand that I welded up, they drain into a pan filled with straw or grass clippings. I really only do four birds at a time, but have found the extra cones useful to start loading up more birds before the others have bled out. If I was really going for speed, eight would be great. I could run birds in batches of four rather rapidly with eight cones.
5 Gallon bucket of water to rinse blood from hands
30 gallon aluminum stockpot on propane burner fueled from BBQ style tank. I use the same pot to simmer large quantities of stewing hens to debone them before canning the meat. I then use the same propane burner to fire up the pressure canner.
Thermometer to check water temperature
Heavy rubber gloves for the person doing the scalding. Not absolutely necessary, but things can get uncomfortable.
Drum style plucker
55 gallon blue drum with water to hold plucked birds
Plastic banquet table as work table for person removing head, feet, oil gland.
5 gallon bucket for unwanted parts
Old cast sink with drainboard that is mounted on a steel cabinet. I came across this in an old shed and the owner gave it to me. I do the evisceration on the drainboard and drop the offal down through the sink hole into a bucket placed inside the cabinet, under the sink.
Garden hose with nozzle to rinse birds and work surfaces
55 gallon blue drum to chill processed birds
Once the birds are processed I usually switch out the giant stockpot for a smaller one to dunk the birds in heat shrink bags.
and of course, sharp knives and people to help