The Holley Blue will be fine if it is the dedicated fuel pump for nitrous. And you are on the right track for the regulator also, you can use a holley reg.. As for plugs, either get some NGK Race plugs or run the Autolites, go about 1 step colder for the 100 shot and 2 steps for the 150. You don't really need a return for the fuel (NOS), but it would be nice to have though to prevent any possibility of pressure creep.
I'm sure some other nitrous experts will chime in to help also. I'm no expert by any means, just an advid user trying to help out a fellow 5.0 guy.....
have fun bro!