Leave them whole so less of the meat is exposed. If possible let the birds sit on ice and let the water drain to prevent the meat from losing too much flavor. Make your final cuts 36 to 48 hours after slaughter and vacuum seal.
Good question. I run a processing facility where we handle beef, pork, deer, and a variety of other animals including poultry. It takes Thirty six hours from the time of slaughter for the rigor to leave the carcass. A good way to hold the birds is in an ice chest for a couple of days before...
I ordered a set from nasco. This kit has a couple of tools that were useful, but I had to supplement that kit with some forceps and probes from a field surgical kit I got from amazon.
Caponizing a rooster is done for the same reasons you would turn a bull into a steer. The meat will be tender and fattier instead of tough and stringy.
Working on the live birds is unnerving at first, but once you accept that the birds may not all make it the work will get easier. I have been working with a guy around Atlanta that has helped me. Private message me and I will share his contact if you are in the area.
I caponized at 7 and 10 weeks from 2 different hatches. Just sprayed the cuts with blue coat. They seemed to heal just fine. Hope your procedures go well.
Castrating the rooster and then fattening them can make them more useable. But preferably you should catch them at 4 to 6 weeks and castrate (caponize) them to grow a large and tender roaster. I have just recently done this to 12 of my cockerels with nice results.