ok, on question 1 - pigs only need to be tagged when they are moved between holdings with the ID of the holding they are going from. Once they have arrived - if a tag gets ripped out, it does not need to be replaced (but you can't legally remove it). So having lost their tags, they do not need to be tagged again whilst they remain on the same holding.
on question 2 Moves within a holding do not need paperwork, so as your land is classed as a single holding, no paperwork is required
So as pigs are moving within the same holding, you do not need to tag them and you need no paperwork!