How long are pigs pregnant? How old are piglets before they are weaned? How much room should mom and babies have? How long after birth or weaning can mom be re-bred without wearing her out? Until what age can you breed a pig?
Wean them at around 4 - 8 weeks, depending on how well they are eating solid feed.
Some are farrowed in crates that give them 25 sq feet or so, and some are "pasture farrowed", and they might have many acres of land. There is no given rule on this.
Sows are routinely bred 5 - 7 days after weaning. They don't seem to be bothered by that. They cycle every 21 days if not bred.
As far as I know, there is not any real hard and fast rule on how long they will breed. Certainly some last up to 10 years.