Thanks all. glad to see that I am not the only one who is overly excited by this project, haha.
I recently just found out about the ANGRY MARINES, and they are awesome! I still have no idea what chapter I want to paint this costume as, but they are a good possibility.
Kelly - The foam I use is insulation foam, the kind they use to build houses... or insulate them, not build. It comes in big sheets and I get it from Home Depot, but most any building supply store should have it. I have heard of the hotwire technique, but have not used it myself. I use a saw for really big cuts, then an exacto knife or pocket knife for anything smaller than that. Hope that helps.