Without the VP wire tapped, does the box automatically shut down the power level adjustments? Or does it just not give you full effect in all 5 modes?

You only get the EZ sized power enhancements (single level) without the pump wire.

So you only get levels 1-5 and no sublevels?

You only get the 80 or so HP gain.
The five adjustable power levels are inop without the pump wire.
You do get some timing adjustments as to when the power will peak, via the "Smoke" level adjustments.