Hi,
Don't worry about pigs jumping over your fence - it's the digging under you've got to watch out for
If you run 2 strands of electic wire or tape at approx 6 inches and 18-24 inches from the ground that should do the trick.
As for introducing others - I think that would depend on what she's been used to. If she's been on her own for a while you'd maybe have to be a bit cautious and I'd go for an older pig rather than a youngster, but if she's been with other pigs it should be okay. Other, more experienced keepers, will be able to keep you right on that one.
Good luck with it, they are incredibly addictive and great fun to keep. Please post some photo's once she's settled in