Hi,
I'm not sure if you're contemplating them for the friendship or the freezer

From what I understand pot bellied pigs are kept PURELY as pets, and fairly high maintenance at that. I've not had them myself - maybe someone else here has who'll be better placed to give advice. But I believe they're very inclinded to become overweight, which would obviously lead to health problems, also I think eye problems are quite common due to the wrinkles on their faces and I think (but again, may be wrong) that they require a specialist feed. They also live for up to 30 years, so it's definately a long term commitment.
As they're normally kept as house pets I don't know how they'd fare if you were intending keeping them outside, but I'd imagine a good, well insultated arc and plenty of straw would keep them warm enough in all but the coldest of weather.
You'd obviously still need a CPH holding number and have to conform to all legislation and I also remember something about needing a licence if you're going to 'walk' them.
To be honest - it's a lot of hassle for a pet, I'd probably go for a dog instead. And if it's meat you're looking for it's the wrong choice - I think you'd be better of with a native 'rare' breed, as they'd be better suited to the environment and give MUCH better meat.
Here's a handy website
http://www.potbelliedpigs.co.uk/But good luck whatever you decide and keep us posted.