Help with the right adhesive for a awesome art project?

Wood glue (or also called PVA ((stands for poly-vinyl-acetate)) ) goes on easy, cleans off in water, is quite cheap, and readily accepts varnish overcoats. Any generic brand will do fine, it's all the same stuff. As for varnish, make sure you get a clear one, gloss if you want it to look shiny, matte if you don't. As before, most brands will be very similar, it just depends on your budget. By the way, that sounds like it would look really cool! Good luck!