In Tuck Everlasting, why does the author state that the first house, the road, and the wood are important?

The first house, the wood, and the road are important, because those locations are central to the conflict in the story.  The first house is the Foster house.  It is where the reader meets Winnie and her family.  The woods belong to the Foster family, and they contain the spring water of immortality.  In the beginning of the story, Winnie wants to run away for a little bit in order to gain some independence from her parents.  

"I'll never be able to do anything important if I stay in here like this. I expect I'd better run away."

Early the next morning, Winnie tries out the idea of running away by wandering out into the woods.  That is where she first encounters Jesse Tuck and the spring water.  That meeting propels the rest of the story forward.  

The road is important because it delivers another central conflict to the story.  The road delivers the man in the yellow suit to the first house. Through blackmail, he is able to obtain rights to the woods; therefore, he owns the woods (until Mae kills him that is).