I have to agree with the previous posters - you're asking for a LOT for very little. A stepper machine won't do that kind of resolution without extreme gear reduction which limits speed hut that wouldn't matter for the size you're looking at. As for G-Code - that's something you're best to contact the manufacturer about. EMC can handle any standard G-Code thrown at it, and has some features in it that some other packages don't - I hand code most of my own work but I don't do, or should say I haven't done any relief milling. To even come close to the accuracy you want, regardless of stepper vs servo you're looking at HIGH DOLLAR ground screws and my bet is you'd need HIGH DOLLAR glass scales for position feedback. Even at short lengths they won't be cheap. EMC can handle all of that, but the mechanics are going to be pricey.
If you do manage to prove us wrong - do tell and brag to the heavens! (and patent anything that isn't already covered and then start manufacturing these cheap high precision units and selling them to payback your school loans).
Every day is a learning process, whether you remember yesterday or not is the hard part.
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