Scary hobo shack and alternate ending - help!

I kind of liked this movie, but ended up kind of confused. First of all, what is that little shack in the forest? Does it have any meaning? I kept expecting it to have some sort of relevance to the Dr. Well/Zachary story, but nothing was ever explained. Was it just some sort of hobo shack with an ax inside?

Also, how were they able to afford that giant mansion in the end?

And finally, for those of you that have watched the alternate endings on the DVD, about that scene where they go to visit Adam's grave and Adam is playing ball... What is going on? The scene before, Greg Kinnear's character seemed like he was going to "terminate" the boy...

Someone help!