The size of the enclosure will depend on the size of the animal you are getting, if you get an animal under 25 grams a 6 quarts tub or 5 gallons tank will be ideal along with proper temperatures, thick layer of bedding allowing your snake to bury itself in.
The main mistake new keeper do is that they do not feed enough, hognose have a fast metabolism and because at first the prey fed is meaningless (pinkie mice) the animal need to be fed more often, at least every 3 to a days.
If is best to feed mice throughout their lives as they sill max out with adult mice, and while a rat pup is the same size they are however lacking the calcium and lean muscle provided by mice.
Something important when ready to buy a hognose is to make sure the animal has fed enough time on unscented and on F/T as it can be tricky to wean them off scented or live prey (and finding live pinkies is not an easy task)
If you are looking for a pet I will recommend a female, males are great but do stay small and have a tendency to be more inconsistent feeder which can get frustrating.
Size wise you are looking at 15 to 36 inches females being bigger than males and also heavier.