I thought I saw something that said Billionaire in a newspaper and assumed it was Walker's father, but I guess it was his brother. Didn't he say his father had been very wealthy? Also, he had paid for "restricted airspace" as well, to keep the village hidden.
Walker and Sigourney's character had the hots for each other, but an affair would pretty much undo what they were trying to create, a perfect society.
I just find it ironic that the "elders" were using mortal terror to keep the kids from the real world, and that murder found it's way into their cocoon.