I currently have my NC dual booted with a CM7 card and according to Google Play, both Bad Piggies and Bad Piggies HD are compatible with it. I haven't installed either, so I can't say how well they work.
You can find instructions on creating your own CM7 card by Googling, or you can buy one off eBay or somewhere else.
You might. If you download the free version (with ads) it will probably work better playing offline.
Not sure if it is a mistake but Bad Piggies now shows 'Nook Color' as supported device.