I've made moulds by using the blue foam from Lowes or Home Depot. Just make sure to use a latex paint over the foam as the aerosol paints typically just eat away at the foam. This works well for one off parts. I made my rear fairing this way. Bad thing was that I did a male mould and so most of the body work was on the fairing rather than the tool since the untooled side was on the outside. I work in a composite shop and we use wax on our tool masters all the time. Too much wax leaves an imprint on the part when you are done, so the trick is to apply the wax in a vertical direction and let it off gas for about 15 minutes. Apply a second coat in the horizontal direction. This helps ensure you get good coverage over the tool. Let it off gas and dry. Go back with a tee shirt and lightly wipe off excess. Make sure you don't do too much and buff the wax off. If you are ever worried that you haven't released it well, take some water and drip it onto your tool. You should see the water bead up well. If it doesn't, you haven't gotten the surface released well enough. Also, remember to put a slight draft on your tool. Parts won't come out too well if you have acute angles or 90 degree angles.
As for mounting the fairing: I took square tubing and creased one side face of the tube with a punch and hammer. This created a V which fit over the frame tubing. I made sure the 4 square tube pieces where planar on the top. Welded the tubes to the frame. Drilled a hole in the fairing such that they were centered over the tubing. Cardboard template helps. Match drill or transfer the holes from the fairing to the 4 tubes welded to the frame. Once you have the holes in the tubes, I attached nutplates inside the tubing. My seat is just velcro'd to the fairing. 4 screws hold the fairing on.
Oh, I almost forgot, I managed to trim the plastic inner rear fender to fit up against the backside of the fairing. Used a silver sharpie and transferred the curve in the fender to the inside of the fairing. Trimmed out the back of the fairing to match the curve.