Really nice! I hope you sealed it with and acrylic sealer. Even tho it's permanent, I don't really trust it, esp. since it will be exposed to the elements - would hate to see all that beautiful work you guys did get smeared or washed off. If you didn't rough up the surface before drawing, there would be nothing for the sharpie it cling to.
If you use wax paper, you will get wax all over your fabric - use the release paper from the fusible web, the shiny side where the fusible was, not the paper side. I keep a bunch of release paper, esp. the larger ones just for doing things like you need to. The fusible will not gum your iron or pressing cloth. The release paper is also great for cleaning your iron from fusible messes - just place your paper on the edge of your ironing board and iron the edge, that will get off most of the junk.
I always prewash my fabric - I don't like how stiff it is, plus I don't want to take any chances of shrinkage. I did read somewhere about prewashing your interfacing, but I've never done it. In all my years of using Craftbond, only recently did I have a problem with wrinkling - don't know if it was the fabric or the batch of interfacing I had.
This might be too late, but I have done applique cutouts, fused them, and zig zagged the edges for extra insurance and they've come out really nice. Take a look at this pic of a bag I made for my daughter - the trick is to leave about a 1/8" border between the image and your cut (that way, you don't have to be so precise in your cuts):