RE: Flying Wing-Glass ship
I don't know how you could be working on the plug, when you're asking these questions, but...
Since this is a small model, I would square away all the design issues first, before considering plugs and molds. Do a search here on RCU or on Google for "flying wing", and you'll find a wealth of information that will get you started. Then, my advice is to make a simple balsa model or two, to prove the flying qualities. Once you know how it will fly, then make plugs and molds.
Using this kind of approach will save you a lot of headaches, and a LOT of sanding.