For instrumentation, I would recommend using a bluetooth OBD-II scanner and an Android phone/tablet running Torque. That's what I'm running in my Prius and it works great. You can add custom PIDs to show you just about everything the car knows,
see this thread on PriusChat for more. Nothing against the Scangauge, I have one in my Escape and love it. But with all the information the Prius has to offer, and the cheaper price ($15 for scanner, $5 for Torque app, $100+ for Android tablet or used phone), Torque is a no brainer.
There is really no reason you use N when hypermiling a Prius. You can easily get the same results by manipulating the gas pedal correctly. B should only be used when going down a large hill, similar to L in other cars. You can actually brake pretty hard using just regen, just be sure not to jab the brakes, or it'll go into "oh crap" mode and use mainly the friction brakes.