Williston is very expensive, you will find a place to stay but be prepared to pay up. RV with hook ups will run you $1000 to $1500 per month. A town house rental is running $2500 to $3500. The experience has been good for me but don’t go out to Western ND blind, you will probably not be prepared.
As far as things to do, there is fish to catch and birds to shoot. But the best thing to do in Williston is make money! Save the hunting and fishing for when you come home.