Any of the British rare breeds would be fine - check the Rare Breeds Survival Truast for ifnormeation. There is a rare beerd sale at Thainstone, Inverurie on 2nd May. There might be pigs there - check Aberdeen and Northern Marts website goanm.co.uk. The catalogue will list vendors, if there are any. Everyone who has pigs has their favorite breed and will promote it.
The more land the better but you have to weight that against the cost of fencing it. There are a number of threads about fencing already.
If you have a look at the Articles section on TAS, we've put our costs on for last year, which will give you some idea of what to expect. Three weaners is reckoned to give a small profit.
Lots of expert pig keepers on here.