I'll give this one a shot...
Kokyu, as you have pointed, is inherint in every aikido technique. What then is kokyu nage, and how does it differ than other techniques? Good Question!
The answer is more obvious then you would think. Kokyu nage techniques are just that, techniques that are based upon "Kokyu" only - rather than Kansetsu (joint locking) waza, Osei waza, Kaeshi (reversal) waza, ...etc. In simpler terms, you would execute the technique using only Kokyu (with irimi, tenkan, irimi-tenkan, or tenkan irimi...).
I hope this clears it up (a bit).