Regards electronics then really it boils down to one standard setup for this size machine to get best performance and it goes like this.

3Nm 4.2a 8 wire low inductance Nema23 motors wired in parallel.
75-80Vdc digital drives
65-70Vdc PSU
16mm 10mm pitch ballscrews on X & Y
16mm 5mm pitch on Z axis.
Good quality BOB
And if you want the very best performance and reliabilty then external motion control card to get away from parallel port.

Yes you can calculate the torque required and probably get away with lower NM motors and possibly use 50Vdc drives along with smaller PSU but the above setup won't cost much more and will be well on top of the workload giving maximum performance while at same time giving redundencey which prolongs life of components as they are not working near there limits all the time.