Most people recommend PVC cages for ball pythons. They're lighter than glass and durable, and hold in heat and humidity well.
As for plants, if you don't want a planted tank where you don't remove the substrate, you can leave the plants in pots and use a substrate like coco fiber or coco chip to pile up around the pot (if you don't like looking at pots ). That way when you clean you can just remove the pots, clean as needed, and replace them in the enclosure after you're done cleaning. I agree that uprooting the plants every month for cleaning would probably damage the plants.
For the custom hides made from foam, you'll want to coat them in grout, paint them(acrylic is usually the best for this), and then seal them with something like the Minwax water-based sealer.