Auk, how about this. I do not post the next steps here and you and I both spend the rest of summer working on our trees and then show what we have done, and the plan for the future?
I got this one for free (workshop at the Cherry Blossom Festival where I attended a workshop - which I attended as we got to keep the tree).
My plans were different - I wanted to find how hard it is to take care for these plants. I am already seeing a few yellowing leaves (2 or 3, not much yet), but I expect that, even while it gets the same care as my other plants, it will get worse. Main reason: the soil. Forget it once on a sunny day and it dries out and shrinks. The result is that, when you water it, the water will not easily penetrate the soil but run off on the sides, through the space between the pot and the soil,
I guess the result is that the soil dries out even quicker, and the problem gets worse. I also guess that's why the advise is to submerge these plants - which I have done once so far. Not tried your tip to submerge it in luke warm water yet.
However, interesting idea. I'll repot it today.