Jim,
Take a look in the composite fabrication forum, theres a ton of threads on plug building, and mold making. Just about all your queations can be answered there.
Also Mike James has a great web site showing you step by step how to build a composite model, from CAD thru plug making, laying up the mold, and finnally pulling parts.
http://www.nextcraft.com/j47_development.html
Hope that helps you out abit.
Jeff