Shevi’i Shel Pesach
The night of Shevi’i Shel Pesach is the Rosh Hashana for mesiras nefesh. When Hashem told Moshe to take B’nai Yisroel right away and flee Mitzrayim, Nachshon ben Aminadav jumped in the ocean right away with mesiras nefesh.
Acharon Shel Pesach
Why is it that the last day of Pesach is called Acharon shel Pesach? We don’t call the last day of Sukkos “Acharon shel Sukkos” or the last day of Shavuos “Acharon shel Shavuos”? The prophet Yirmiyahu said: “Therefore, behold days are coming, says the L-rd, [when Moshiach arrives] when they shall no longer say, "As the L-rd lives, Who brought up the children of Israel from the land of Egypt…" (Yirmiyahu 23:7).
We call the final day of Pesach “acharon”, the “last”, because we demonstrate our faith that this Pesach will be the last one in exile because Moshiach will soon come and we will not celebrate Pesach as we do now.
They say earning a living is as hard as the splitting the sea. The Chiddushei HaRim said that just like the sea split suddenly when the Jews almost lost all hope, so too when a person has no hope for a livelihood and is in a deep despair, Hashem suddnely sends him a parnossa.