Kongorilla, great to hear you're having a crack at it. Unipolar steppers aren't a problem at all, no, basically anything the motorshield can handle will work fine.
Re torque - I have no idea what's good or bad to be honest, I just found some that supplied "enough" and stopper looking after that. The motors I've been using are these ones:
http://www.ebay.co.uk/itm/5-x-NEMA-17-Stepper-Motor-ETS535-0-9-deg-4-2V-/180740649234?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item2a14fb7112#ht_1031wt_1396
The spec sheet only cites 425mA draw - at least I'm assuming it's mA, doesn't even actually say what unit it's in.
Torque-wise, if you are using counterweights, you don't even need very much torque, since you're moving weights around rather than holding them. Your counterweights should be heavy enough so that your gondola hangs about in the upper-middle of your surface, so the motors really only have to "lift" from the neutral point up to the top of your page, and "push" down to the bottom. The more torque you have, the bigger the area you'll be able to cover reliably. Mine is ok everywhere all over the surface, but with an extra bit of weight that I usually add to the gondola, it struggles when moving fast right near the top and misses steps. If I added a bit extra weight to the counterweights I'd be much better off.
I'm no expert either, but voltage seems not to be listed on a lot of steppers, I have read the reason why somewhere, but forget it now. Something to do with inductance? A lot of stepper drivers run very high voltage at peak (30v +), but I have a couple of motors I bought ages ago before I knew what I was looking for in the spec that are dead low voltage, like 3v, but they draw 2A. So I blew up a couple of motorshields using them after a while, but you live and learn!
Current/phase is what you're looking for.
Cheers!
sn
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