1) Question: Why is it the middle Matzah that is broken in half?

Answer: When partaking of the Matzah, the sequence of the Berachos is; a) HaMotzi; b) Al Achilas Matzah. The first Berachah is said on the whole Matzah (as we do on every Shabbos and Yom Tov); the second Berachah is said on the broken Matzah (see ref. 105). Following the principle of not bypassing a Mitzvah object, the one to be used earlier in the sequence is placed as the upper Matzah.1

2) Question: Why do we use three Matzos?

Answer: We begin every Shabbos or Yom Tov meal with two loaves. At the Seder night we add a broken loaf to symbolize the Bread of Poverty (see ref. 105). [One could argue that 2½ Matzos would suffice. However, in order to beautify the Mitzvah we begin the Seder with three whole Matzos].2

3) At the Shabbos and Yom Tov meals, the two loaves are placed next to one another, yet in between the three Matzos for the Seder we separate with a cloth. The source for this is in Kabbalah, to indicate that each Matzah has a distinct purpose.3

4) Question: What is the reason for the layout of the six items upon the Kaara?

Answer: The items to be used earlier are placed closer to oneself. This is in line with the principle of not bypassing a Mitzvah object. [An exception is made in the case of the Chazeres; although used later on, it is placed closest to oneself. Due to its bitterness the [maror and] chazeres do not have priority regarding berachos said over food. For the same reason it is acceptable to bypass them on the Seder plate.].4

5) We say a separate berachah — HaGafen — before drinking each of the Four Cups. This is because each one is a separate mitzvah.5

6) When the Beis HaMikdash was standing, one focus of the Seder night would be the Korban Pesach. To acknowledge this omission we begin our meal with eating boiled eggs, a food given to mourners ר"ל.6 However, adding unrelated aspects of grief to the Seder night is quite inappropriate, since the theme of this night is to celebrate our deliverance from Mitzrayim, and the anticipation of the full and redemption through Mashiach.7