And you should start filling the seams with plasti-dip or hog mog after you detail with a dremel. So switch fill the seams and detail with a dremel around. And an ODST would be possible, not an easy start, but possible. Its better that you start experimenting with the foam before you make a suit, otherwise your final product may not be what you were expecting. A hot knife would probably be your best bet for cutting the mat, a razor blade works just as fine, but the mat eats up blades like crazy! Besides that, it looks like you got everything else in order. In my opinion, I think strapping would be best in any case, wheather the material is comfortable or not, it all depends on the adjustment and how you want the suit to fit on you as the final prduct. Hope this helps and hope everything comes out great for you!