Hi valg
Sorry can’t answer your question re. quantities of food. It depends how much food the hogs are getting in the wild and from what other people leave out – whether anything else is also eating it i.e. cats, etc. You might find you’d like to get a night camera to give you a better idea of what’s going on.
Re the holes in the lawn. The hogs here don’t dig holes in the lawn, although I believe hogs will dig for things – possibly in borders rather than lawns where it would be easier. Usually the hogs here wait until part of a worm appears and then grab it and rapidly reverse to pull it out of the hole! I remember seeing a website where they showed pictures of how different animals dug in lawns/grass. Sorry, can’t remember what site it was, but you might be able to find something on Google or the like which shows something similar to the holes you have.
Well done your husband building a hog house! Hope you get a tenant soon. Sometimes it takes the hogs a while to accept them, but other times they move in almost straight away. You could try leaving a twig, flower or some rolled up paper (that sort of thing) in the doorway to see if anyone is going in or out. Often the nesting material is as important as a hog box – they still need to build a nest inside for i.e. a birthing nest or hibernation nest. So make sure that you leave suitable materials in the vicinity – leaves (medium sized are preferred) long grasses, etc.
Good luck and happy hog watching.