I think the veggie society has some info on the 'free-range' labelling of eggs and such (there are varying conditions including barn eggs which are almost factory-ish depending on the farm so dodgy), but I buy free range because I trust the labelling - mind you half the time our eggs come form waitrose and are part of some sort of rare breed survival programme (wierd when you think about it but ...). So it's also worth checking what the shop's ethical policy is (eg Co-Op) and what labelling they use.

As for pigs, intensivity can vary, there was a large pig farm Na'Lon and I walked through whilst trying to walk up the river to Islip years back. there each sow and litter had a ten foot fenced patch with feed & water troughs and a corrugated arch for shelter; twas very muddy too.