Hi Christina
You do need a health background check - has he needed any vet treatment, general health, food preference and as Jake said his birthday.
He would need to be kept seperately from the girls as he will mate with them so he would need "solo" playtime and cuddle time.
If I know where any rescue hoggies have come from and know more of their background then I do not have the same concerns as if I was taking a hoggie in from a background I knew nothing about - if I know nothing about them, I generally treat for mites and in some cases ticks.
As long as you keep him to his home, seperate play time and cuddle time then this should really be sufficient in this case.
If you have the opportunity to go and meet him first and see for yourself how friendly he is -if you find he is friendly, the whole process of him moving to a new home will be a lot easier than taking on a huffy hog.
Good idea to weigh him and get his supply of biscuits and then gradually mix in your biscuits to change him over gradually.
If you need anything, please ask away xx