So speaking of the farm, and any casual posters can tell I'm on rewatch and I'm bored and trying to make things fit.
My family has a farm, that has one house and one stable for horses and a pen for chickens. We didn't use either horses or chickens because my family grew tabbaco. Or tomatoes, take your pick. There are stables and pens we have never used. One decade was a life choice, now its why not tomatoes? Way more land than we'd ever need and we haven't sold a tomato since I was five.
If I had to guess Sissy's farm, while not a real front is more an excuse to keep autistic Harlan away from the city. Lots of places for him to play, and he didn't have to interact with people who wouldn't get him.
Eta: regarding Ben, I think the kids were way more powerful than Reginald understood. We probably are all just learning as they are the cusp of powers.