The point of view in this excerpt is definitely third person, because nouns such as Dorothy, and pronouns such as she are used throughout to indicate third person.
However, if you also need to decide whether it is limited or omniscient, I'd choose limited - because we can only see what she is doing, and not what she is thinking and feeling.
Introduction. You state it in the introduction, so that you can state your claim first before the body paragraphs. You also should re word the thesis statement in the conclusion paragraph.