Whatever you do, don't scald with literal boiling water, that's way too hot. In my experience, over 160F is too hot, I aim for it to stay between 140-150. I add a little Dawn dish soap to it and dunk then swish, pull out, dunk and swish, and keep doing that until the feathers wipe off the legs rather easily. That way they pluck well, but the skin doesn't tear. The wing feathers and tail feathers are always the hardest because they have the longest, thickest quills; if you keep scalding until they come out well you will probably overscald. Needle nose pliers help get a good grip.
Watch as many YouTube videos as you can before you start, that helps a lot, seeing how other people do it. Personally, I'm liking the broomstick method the best so far, and as long as you cut the head off they bleed out fine. I actually like to use a scalpel while processing, it's super sharp and short enough to really get in exactly where I want it.
Any bird will be tough if you don't rest it long enough for rigor mortis to pass, typically three days in the fridge or ice water. Any bird over ~16 weeks is going to be tougher than store-bought chicken. Anything over 5 months you really want to cook low and slow or pressure can. This is why spent laying hens are called stewing hens, they need to be stewed at low temperature for hours in order to be tender enough to eat.
