Hey you might want to rethink about putting slits instead of holes for the lacing. Slits will tear out easier than the holes will. Also build up the acrylic in thin layers, thick layers will crack easier. Make sure you cut your resolene 50/50. Look at some of the posts on seats by using the search in the upper right corner. If you can't find something or not sure just ask there are several great seat builders here benliliy being one. You are on the right track I was just referring to some of the things in your list.
David