God told Avraham (Abraham) that his children would be living in “lands not their own” and would be enslaved for 400 years, Yet the Torah states that the Israelites were in Egypt for 210 years.  So we say God “calculated the end” (chisheiv et ha'keitz) of the enslavement: He started the counting from the birth of Avraham's son, Yitzchak (Isaac), until the Exodus (a total of 400 years), as follows:
 
Time from Birth of Avraham's Son to Going Down to Egypt

• Yaakov (Jacob) was born when Yitzchak was 60 years old.
• Yaakov told Par'o (Pharoah) (when he and the rest of his family entered Egypt) that he was 130 years old.
• 60 + 130= 190 years before going down to Egypt

 
Time in Egypt
210 years in Egypt
 
Time from Birth of Avraham's Son to Exodus
  190 Before going down to Egypt
+ 210 In Egypt
= 400 years from Yitzchak's birth to the Exodus.

The seder table also has a stack of three matzas (matzot), representing, among other meanings:

• Cohen-Levi-Yisrael:  The three divisions of Jews
• Abraham-Isaac-Jacob:  The three forefathers

These matzot are used later in the seder for the steps of Motzi and Matza (top and middle matzas); the middle matza becomes the “Afikoman.”

The Blessing for the Children has two parts:

1. Introduction
   For Boys: “Yesimcha Elohim k'Efraim v'chi'Menashe”
   (May God make you like Ephraim and Menashe)
   
   For Girls: “Yesimeich Elohim k'Sara, Rivka, Rachel, v'Leah” 
   (May God make you like Sara, Rebecca, Rachel, and Leah)
   Note The formula asks God to make the boys like Ephraim and Menashe but to make the girls like Sarah, Rivka/Rebecca, Rachel, and Leah. We might think that Sara, Rivka/Rebecca, Rachel, and Leah should be paired with their husbands, Abraham, Isaac, and Jacob instead of with their grandchildren and great-grandchildren. Yet, while Isaac and Jacob had the advantage of growing up in religious homes and in Eretz Yisrael, all of the fore-mothers as well as Ephraim and Menashe lived righteous lives even though all grew up in bad environments outside of Eretz Yisrael.
2. Priestly Blessing/Birkat Cohanim (Numbers/Bamidbar 6:24-26)
   This is the blessing that the priests (cohanim) use when blessing the Jewish people.  For words to the blessing, please click here and scroll down to "Birkat Cohanim": http://practicalhalacha.com/blessings#B.

Avraham was commanded to circumcise himself and all males in his household. From then on, all healthy Jewish males were to be circumcised when they reached 8 days old.
If there is any question about the baby's health, the circumcision is delayed or, in rare cases, not done at all.
The primary obligation to do the circumcision is on the boy's father. Since most people are not skilled surgeons, the actual cutting is usually done by a highly trained expert, called a mohel, who is appointed by the father. A festive meal is eaten after the circumcision.  A minyan is preferred, but not required, for a brit mila.