Not much of a capenter/many plot holes

So if they had just moved into that lovely house, how was he friends with Billy since high school and why were the kids new to the school..Where did they come from? And if he was such a good carpenter/contractor, why did he move into such a lousy looking house and why didn't he fix it up a little bit, or at least fix the roof from leaking..I know there's a lot of plot holes, but it was a funny movie..