One other important symbol is the chest hair that Jem shows to Scout, signifying that he is now entering into manhood and will in some ways soon be separated from her because of that change. This goes along with some of what he is forced to deal with in the chapters as well.
A good example of irony is found when looking at Aunt Alexandra's behavior. She is unwilling to have someone over for dinner, someone she considers beneath them, but she gives the other ladies a very hard time about their hypocrisy at the missionary tea. We don't expect this from Alexandra but it provides a good example of the ironic behavior of some of the characters.