Hi Geoff, I cut mostly portraits of people, animals, cars and scenic pictures using 1/8" and 1/4" Finnish birch plywood, also Oak plywood. I prefer the birch for the portraits and oak for the scenic pictures. I feel the grain of oak takes away from the portraits. I use 1/8" luan plywood as a backer, either staining or painting it. I use just a clear finish on the cutting. Clear tung oil finish or a water base spray if I am in a hurry. I sand the plywood with a random orbit sander before applying the pattern. The blades used now require very little if any sanding on the cut edges. Like Xray, I use a small torch to remove the fuzzies from the back side as well as an assortment of tiny files.
Mike is great for blades, any questions on what blade to use for a particular job, just shoot him an e-mail. He is always very helpful.
Will be anxious to see some pictures of your work.
Mick
Delta P-20