[@Project] nobody really knows and it's never explained. Every jutsu essentially contains yin-yang chakra, but very few use purely yin-yang chakra. Genjutsu for example uses yin chakra (because yin is 'the spirit' and thus not tangible) and mokuton (wood release) uses a lot of yang elements because yang represents creation.

Essentially, if you are using chakra to create something that is not tangible, it's yin, if you're using it to create tangible items, it's yang, and if you're creating life or items that possess qualities of life and sentience (like kage bunshin I think) it's yin-yang. 

Like all jutsu, it's only as powerful as the user. As I said before, Madara using a C rank fire jutsu is more powerful than a chunin using an S rank fire jutsu for the first time in their life.

Healing jutsu uses a lot of yin-yang elements I believe. 

Everyone can use it, very few use PURE yin yang chakra.