Kokyu (breath/life) is the physical expression of ki.
Chris, I think part of the confusion might be if you haven't been shown how ki relates to our own connections of muscle and tissue inside, how they can be conditioned and trained via breath and intent to be something unmistakably felt as an unusual kind of strength.
Then kokyu becomes the management of these internally trained facets along with optimized use of the natural forces acting upon us (gravity/ground or heaven and earth depending which schema or definition you want to use) such that we blend them in a multitude of ways. As the usage improves in strength and sophistication it is much more than good posture and alignment to the extent that it should be felt by another person when they put hands on you or even cross weapons if you're really good.
Then aiki is how you manage all that stuff and additional forces added by a training partner, opponent, etc. Viewed in that light, aikido, with it's taiso warmups/exercises/conditioning as ki/kokyu, then aikido with partner practice and waza - makes pretty good sense to me anyhoo.