Ok Mike, I'll see if I can explain straight/offset/helical to ya.
A straight fetching is that, perfectly straight online with the center of the shaft. If your vanes are straight, you can look down the base of your vane and it will be perfectly online with the center of your mock and the fieldtip/broadhead.
An offset is taking a straight clamp and adjusting the jig so the vane is slightly offset from center. The base of the vane will start in the center of the arrow and have a slight angle left or right away from center, hence the
X degree of offset.
Helical is a really hard turn or curve in the vane, very noticeable. Think offset, but more hardcore of an angle. Like others said, it is not great for a WB, but it gets the arrow spinning faster.
Hope that makes sense man.