Yes, I used full side art coverage in a couple projects. I would suggest not skipping the painting though. Painting helps seal the wood, and gives the decal's adhesive a better surface to cling to. Even if you just put a couple rough coats of primer, and sanded them down smooth, that should be good.
You can get prints from anywhere really. Adhesive vinyl printing is extremely common, so check out your local print shops, or you can opt for places like gameongrafix, or printshock for your art prints.