I intend to build my flow through bin about 32" by 72" inside. It will be 28" deep above the bottom cross members. Do these measurements sound appropriate? I make a potting soil mix at home by this recipe, 2 parts peat moss-2parts orange mortar silica sand-1 part vermiculite, and 1 part perlite. Will this mixture work for the initial bedding? I intend to put bedding on top of wetted cardboard placed on PVC pipe. Start the bedding about 6 inches deep and cover with shred news paper. Does this sound OK? Now last question. How many worms to order to start the bin and what kind?