That's not much overdrive, I take it this will be slow (single stepping or low RPMs)?
Last drive I made was a quad powerSTEP01 driver, that pushed up to 80V into 5V motors -- these were lower resistance and higher power than your motor obviously (a bit smaller than your fist), but the excess voltage is all about speed, and it's consumed by leakage inductance, not necessarily dissipated as power. Under load, the motors used an ampere or two at top speed and voltage.
Those had harnesses around a meter long, not much reason to worry about them. It's just additional inductance and resistance, and if you're stepping slowly, and comparing with a 24 ohm coil, it really doesn't matter.
As for number of wires, I've seen 8 or 9 wire steppers before, not sure what the extra ones are, never investigated that one -- most are 4 or 6, the difference being a matter of convenience.
Tim