MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.
Not really a requirement, Nema 23 is just a convenient form factor and I bought several of these motors (they are cheaper in bulk) so I use them for different projects. Any other BLDC would work too, the cheapest ones are probably for RC cars and there are also NEMA32 adapters for them here on Thingiverse. You shoult select one with a "relatively low" RPM (low KV), also they don't have hall sensors so you need a sensorless driver. The driver board I specified, version 7 is with hall, but there is a nearly identical one (version 6) without hall.
If you want to run a DC motor you need a brushed motor driver or build one with a MOSFET and some resistors. If you put 50% PWM through a MOSFET on 12V connected to the motor, then from the motors point of view it is like running it on 6V.