Your having fun! RE RS232, in my home brew software I have to calculate the estimated time of a move before it's sent. It's a servo machine that'll do 5m/s if you let it but the reality is you have to wait till the machine card is ready to accept another move instead of hammer it wth commands.
Anyway, these used to run on CAMGL, a sort of HPGL for routers. Sturdy little devils though, good stiff construction, big bearings and proper ballscrew I think. At the end of the day you could just pulse the steppers down the parrallel. Re homing, sounds like are there endcoders on it, real acurate would be crossing the home switches, then stepping going back to a rising edge. Very repeatable.