Alfalfa hay yields are 4-5 tons per acre in our area. Of course Management Intensive Grazing can move these stocking rates up and also helps with rooting. Fencing I am using all electric fences for our pigs. Woven wire will work, but isn't as convenient or affordable. The same basics for other animals apply to pigs.
Sows are probably one of the easiest animals to keep in.
The only time they ever get out is when I put them in a pen and they can't see the fence. Little pigs are a different story. Therefore you need a huge fence energizer if you are going to fence in pigs less than 40 pounds with electricity. It will work. I recommend a minimum of a 10-joule fence charger for little pigs.