Good thing to discuss. there are an awful lot of folks out there that train "Internal Chinese martial arts" that know nothing about the 6 external harmonies. And it is easy to notice, just by watching their form
For the record, in China, Shen is "Mind" I have a post on here somewhere that explains that better as well as the misconception may have about Shen
And my favorite explanation of Qi (energy) comes from the TCM people I know from China.
Strong Qi you're healthy
Weak Qi your sick
No Qi your dead
Another good saying to know Yi, Qi Li. Which you did cover. Thought controls energy, energy controls muscle
Story about breathing; My shifu use to say the same exact thing about breathing, when asked, that his Shifu (my shigong - Tung Ying Chieh) use to say. When asked about breathing the response was.is "Yes you should"