Pigs don't need much space. I think it is more of a preference involving smell and having the animal raised in a decent area. I will tell you their are the cleanest livestock animal I have ever raised. They did not pee and poop in there bed or just anywhere. It was always a specific corner. Happy raised animal makes for better meat. Our pen is probably 15wx30l more of a rectangle. That is what we had open and available so that is what we used. We only raised one pig each time. We skipped last year and we are doing 2 pigs this year. We got both the pigs we raised in spring and butchered in nov/dec. they were big pigs....we took home over 200 pounds each pig of meat. Feed varies per area....but grower is $10 a bag in the good weather. They will pretty much eat what ever though. The loved bread and milk. I don't feed any of my animals raised for meat meat. They love alfalfa. You can feed pigs pretty cheap.....call some of you mill yards and get screenings of wheat, peas, soak their feed the night before for the next day wheat expands and they don't need that much dry and does nothing for them. They like grain/cracked corn is pretty cheap. I mostly feed grower mixed with cracked corn 50/50 and alfalfa. Lots of scraps they love veggies. This year we are gonna use electrical wire but before we did not just hog panels. No problems with the ones we had getting out. If I was to redo just the hog panels I would dig a trench and inset them at least 6 inches for rooting. Pigs root for many reasons and about all they have to do. I do not feel it is right to stop them from doing it. They love to play. You can put old tire, ball, shoe, a piece of garden hose out there like 18 inches long, mine loved the plastic feed bags to play with.....but most def. need a way to offer water to allow them to cool themselves and they love mud. They cannot sweat to cool them selves their body does not have that capability. We made a big hole like the size of a kiddie pool and we would fill it at a min. once daily with water I would let it fill while I did my chores....feed the other animals etc. sometimes I would rest a sprinkler in there sideways through the fence to fill up the hole....they loved the mist. You want to worm them too. First bag of feed I feed is medicated....I get my pigs when first able to leave mom.
So much to learn for sure....hope this helps.