no extrusion coming from E0, what next?

So once I connected E0 extruder to X (as well as bringing up the heated bed and the hot end) I was able to manually extrude. There is no fan on my RAMPS, but considering that X/Y/Z circuitry works fine and that F1/F2 don't trip at all with heated bed or hot end, I'm wondering if E0 is fried.

Can I hook up my extruder to E1 somehow and specify that in the software (Repetier-Host)?

If I hook up a multimeter, what voltages should I expect from a healthy E0?