I recently took a class where we did lots of applique. We were instructed to spray starch (Mary Ellen's best press) the base fabric so that it had a little more body for stitching. Then use Heat & Bond lite (or Steam-a-Seam) ironed onto the back of the applique and iron it onto the fabric before you stitch it. If you still need it, (and you probably won't) add a light weight tear-away stabilizer to the underside of the fabric behind the applique before stitching.
Your appliques are awesome. It should be a great success!