I can’t look at the wiring right now, but I can help you out with the wasteboard holes. First, you’ve got to make sure your stepper motors are calibrated. It doesn’t do any good to tell them to move the bit over by X distance if it really moves Y distance.
As for spacing the holes, you can use the replicator app in Easel. Just make sure you tell it to make the spacing 75mm-holesize. As in, if you choose to make an 8mm hole you would want to tell it to put a 67mm spacing between holes.
You can find videos I made on stepper calibration and sacrificial wasteboards by going to this forum: X-Carve Maintenance/Troubleshooting Videos - Add Your Own!