Laura, I saved the juices from the same recipe. I reduced it down a bit in a saucepan, cooled overnight in the frige, then froze it in ice cube trays to use as Nemesis suggested + anything that calls for water (even sauteing greens, etc.) Not sure about the nutritional value, but refrigerating it turned it in to a bounce-a-quarter-off-of-it jello, so it least has a healthy supply of gelatin/ collagen. Tasty stuff, IMO.

Use it as a soup base, or toss in the crockpot with a heap of veggies and let it cook all day. I wouldn't "re-use" stock more than once, though.

The leftover liquid is chicken stock if the chicken you cooked still had the bones. This is no different than any other broth or stock and can be used as desired. As mentioned above, I wouldn't keep it more than a few days in the fridge but if you freeze it in portions you can use it instead of water whenever you want extra flavor.

Very nutritious. If it is pure chicken juice, just heat it, season and drink. Fabulous! Lots of gelatin in there, and loads of other goodness.