I can vouche for everything you have said having rescued three retired racers. Our latest is fast asleep in the bed next to me right now.
Someone in this thread mentioned a raw meat diet. I have never heard of a rescue having such a diet. I know at the track, they are fed horse meat, mixed with vegetables, Gatorade and multi-vitamins.
But we feed our grey kibble dog food with a little bit of organic yogurt to keep her regular.
And yes, they lounge/sleep 16 hours a day, lol!
I mentioned the raw meat diet.
This stems from the theory that dogs are pure carnivores. The only vegetables they get in the wild are usually only what's found in the intestines of their prey, which is a pretty small percentage compared to the amount of meat/bone/tendons, etc. they eat.
Here's a link that talks a littl bit about the B.A.R.F. diet. (Bones And Raw Food)
Raw Dog Food: Dietary Concerns, Benefits, and Risks
It's humorous to watch them eat things like chicken legs. Unlike humans, which eat all the meat off the bone, a dog eats a chicken leg like we eat a burrito, i.e.: they start at one end and chomp through it a little at a time until they get to the other end.
As far a choking, they don't swallow any large chunks of bone because it all gets chewed pretty thouroughly before they swallow it.
Their poops are pretty small, too. Because they digest all the meat, the only thing that comes out is the bones. If you were to leave the poop on the ground, after a few days it turns white and chalky and will eventually break down to a powder.
There's no need to thaw frozen meat, either. To the dog, it's just a meat-popcycle. The frozen meat is no harder to chew through than the bones/tendons.