One water bottle and dish is enough for them. I don't they're territorial when it comes to pig stuff.
Since you have 2.5x6 grid for a cage, you'll need a support underneath if you're going to have a second floor. It might collapse. I think you should block the second floor. Though the choroplast will do fine. I saw some pics in the gallery that their deck is open - no walls on the side. Its up to you.
Its good that your new pig and Monti got along together easily well.
