1. The Gemara explains why Matzah is called "Lechem Oni."
2. There is a dispute about why eating Charoses would be considered a Mitzvah.
3. The Mishnah discusses rules of asking the Four Questions ("Mah Nishtanah").
4. Even if a person is making a Seder by himself, he must ask himself the Four Questions.
5. Raban Gamliel: If one does not say three specific things on Pesach night, he does not fulfill his obligation.
A BIT MORE
1. One reason is that the word "Oni" is written the same as the word "Ani" ("poor person"), which teaches that just as a poor person eats only a piece of bread as opposed to a whole loaf, on Pesach night we eat a broken piece of Matzah.
2. One opinion is that Charoses serves as a remembrance of the Jewish women who gave birth painlessly under apple trees so that the Egyptians would not be aware of it. Another opinion is that it is a reminder of the cement with which the Jews were forced to build in Egypt.
3. A son is supposed to ask his father these questions. If the son does not know how to ask these questions, then his father should teach him how to do so.
4. If he is with his wife, then his wife should ask him the Four Questions.
5. These words are: Pesach, Matzah, and Maror.