I am responsible for answering questions at the Passover Seder, but one that was asked of me I can't answer. Why is there so much significance to the number four in the Haggada: For example: Four questions, four sons, four glasses of wine.
The "four" concept relates to the four promises God made to Moses in the verse: "I will take you out of the forced labor in Egypt, and free you from their slavery; I will liberate you ... and I will take you to be My own nation." (Exodus 6:6-8). Each of the four phrases in this verse describes a unique stage of redemption.
Four represents exile, being scattered to the "four corners of the earth." Correspondingly there are four levels of redemption from exile.
Four also represents growth, spreading out in all four directions. Passover is the time of the birth of the Jewish nation, who are to fulfill God's blessing to Yaakov to "spread out to the west, east, north and south." (Genesis 28:14) Pesach is also in the spring, a time when God's blessings are seen to increase in the world.