japanpsyhic,
The choice of shape and glaze color is largely an aesthetic issue, the real concern is the size. You must choose an appropriately sized pot, not too small nor too large.
Would a pot change, soil change and trim be too stressful?
When re-potting, changing the soil is often one of the reasons to do so. Since your plant is in poor draining soil, re-potting can provide definite benefits. Josh suggests not doing all three at once, and I'll defer to him on that issue as I don't grow this species, but the first two usually go hand in hand.
https://www.bonsai4me.com/SpeciesGuide/Carmona.html
I checked the site you suggest and frankly I find myself unsure if I would use their product or not. The list of components sounds pretty good but I have a few concerns. First since Pine Bark is listed first, am I to assume that it is the primary ingredient? Sphagnum peat moss is also included which, in conjunction with the bark, may be too high of a percentage of organic components. I also have some concern about the size of the particles which is difficult to discern from their picture. Are you committed to using this vendor?
Norm