From the text:
"Perhaps. In a bit," said the man. "But I'd like to talk to you first. Have you and your family lived here long?"
"Oh, yes," said Winnie. "We've lived here forever."
"Forever," the man echoed thoughtfully.
At the start of the fourth chapter, Winnie is outside playing in her yard. The man in the yellow suit arrives at the house and begins asking Winnie questions. He wants to know about her family, how long they've lived in the area, and Winnie responds that her family has lived there "forever." For Winnie, forever means a long time.... for the man who's searching for the family that lives forever means "forever".
Please post your questions separately.