What position does Jack receive when Ralph is elected leader? Why does Ralph feel that things have changed from bad to worse? What island did the plane land on? Why isn't the pilot explained?

Jack is in charge of the choir, they would become the hunters or "army". Ralph finds it difficult to control the boys' primal chaos. Jack can manipulate them. The plane crashed on the island they are on. Golding wanted all adults, including the pilot, out of the picture.