Alternatively there is the Southern Magician feat (Races of Faerun pg. 168) that functions similarly and overall serves the same purpose, however you're required to be human (in this case, your thrall would need to be human). While in both cases the spells are cast as an arcane or divine version of themselves, one changes the source, while the other does not. But for the purposes of learning the divine spells as psionic powers, still works.
Regarding increasing your ML, there is always the option of Power-Link Dragon Shards, although they're pretty cheesy and can make psionic powers get out of hand pretty fast. They also only apply to your ML when manifesting a power, they don't give you access to higher-level powers. And yes, between monk 1, totemist 2, and thrallherd 1 youd be at -4 ML, so in such a case the only option would be the drop the level of monk to maintain 9/8/8 powers/arcane/divine, but then that isnt really the same character you envisioned by that point probably. If you did keep the monk level youd be at 8/7/7, i guess it comes down to if you desire flurry and unarmed damage progression over 9's and 8's.
As far as feats go, yeah you'll be pretty feat starved, ( quite a few gish's are) moreso in this case since your levels will be all over the place. DCFS is entirely possible with this character, although i shy away from things like that >_> Alternatively theres always psychic reformation to repick your feats as you need them, or feat leech to steal some feats from a few thralls believers.
