Ah you've chosen an 8-wire stepper so you can choose whether to wire it unipolar or bipolar - wise precaution! However that specs don't make it clear if the figures are for unipolar / bipolar-series / bipolar-parallel connection. You will have to measure the winding resistance to work that out for certain.
The stepper driver you've gone for is unipolar and doesn't do constant-current driving other than by a series resistance in the motor supply.
The motor has low impedance windings so you'll either have to run a low supply voltage or add series resistors in the supply to the driver board (the latter has the effect of approximating constant current drive and giving faster stepping rates - but at the expense of power loss to the series resistors (which will need the right power rating).
You have the option of upgrading to a bipolar chopper constant current driver later.
You mentioned worries about the torque needed - have you calculated/measured the torque you need?