RE: Blue foam fuselage
I think leaving as much foam in place is a good idea. The foam can really offset the buckling of the skins. If the weight is equal, between leaving the foam or taking it out, you would use a little less glass to offset the weight of foam. The skin would be less pucture resistent but the structure will be stiffer. If you glass the inside of the foam structure it will become even stiffer.