Sorry, you are right, I had a typo in the torque value. 
The motor model is a bit weird. There is a sticker that state: 42HD4428 from mocotech.cn, but there is no such model in the supplier website. I would think it is a 1.8 degree per step, as 0.9 is still not that common in low-cost routers. Also by judging that the guarantee accuracy is 50 microns with a lead screw, it does not seem to be the fancy high resolution one.
The VCC is correct, it is boosted from 24V to 42V, which improve transient behaviour for the steppers.
For the onboard MCU thingy, I have to disappoint you 
The stepper signals (STP, DIR, ENā¦) go from the main controller directly to the stepper motor driver. There is no interaction between stepper and the MCU. For this reason it is a waste of capabilitiesā¦ the good thing is that the stepper driver+DC booster and the MCU are on separate PCB. So if you are brave enough to design a completely new PCB with a TMC for the linear moduleā¦ But it comes with the trade off of lower torque/max speedā¦ and I wonder why I know all these stuffs, maybe something has been tried 