Jonas notices that his memories are fading a bit, which is what he and The Giver had expected: as he moves further and further away from the community, the memories should be released to the citizens and thus fade from his mind. As the days go on, the planes become less and less frequent. Finally, they stop altogether.
The phrase to look closely is the correct choice. If you add the words look closely into the line, it reads Look closely at the lines, making it correct.
