Hugh, my opinion is your last post is pretty right on - the breathwork is something that exercises the ki when you do it with a method where your breaths build pressure. (meaning in normal relaxed breathing, you are free to make the body increase in volume rather than pressure. If you add constraint on purpose, then you increase pressure more and volume less - reverse breathing is one example.) So, where you direct the pressure to directly affects what parts you are training. Working with the chest is distinct from working with the lower abdomen. So, there you described breath-based ki training that is directed toward 2 different spots. One was chest one was abdomen.
My key point is just that the breath can be used to exercise or condition the very same structures that the intent actively controls: they both affect the same "ki."
So they would work together in exercise sessions as a work-out. Then, in usage, you just have your "on" state, body filled with ki, and then the intent is used to manipulate force by manipulating the ki.
(Also, the variant I heard, I think, is "Mind leads intent, intent leads ki, ki leads power" which is interestingly different)
I don't think this is very different. If we had the right vocab, I think it would be said the same each time. We need words for:
- the "mind" which is your conscious self, with desires to get things done through goal-directed behavior
- the "motor intent" which is related to motor behavior and precedes or is coincident with motor actions... it is the first step of a motor behavior and thus is "lead by" the mind as defined above
- some mysterious tension in the body that ends up controlling how the body bends and how force input affects the body ... this is what is triggered by "motor intent" as defined above
- muscle contraction, which generates force. This force would be manipulated subject to the state of the mysterious tension referred to above. So what we call "coordination" would come from the mysterious tension mentioned above, whereas strength would come from muscle force
- total effective ability to do things, which in some people depends heavily on which force-generating muscles (see above) are flexing, but in others may have more to do with the ground reaction force being combined with attackers' force input by the mysterious force-manipulating tension above
In Chinese there is xin, yi, qi, li, jin, in order of my list above. (I am sure my explanation is wrong according to others, so ok, how so?) So internalists would try to develop and specialize in the jin instead of the li. (Replace force-producing specialty with force-manipulating specialty.) Well, O-sensei's vernacular may not exactly match the Chinese, but I think Chris Li and Dan Harden and others are doing a great job with figuring out how O-sensei's education in Daito Ryu may have been connected to this vernacular. The next step (also being looked at) is how his views may have changed or stayed the same throughout his life. Personally, I'm all ears!