1)
What is the significance that nothing will terrify you?
1.
Devar Eliyahu (20): This will be in Gan Eden - "v'Inisich Lo A'anech Od."
2.
Malbim: [The grave] is unlike this world, in which many things terrify - desires, wars of the Yetzer ha'Ra and [evil] occurrences.
2)
When will many seek him?
1.
Devar Eliyahu (20): When he is in Gan Eden ha'Elyon. These three (the grave, Gan Eden and Gan Eden ha'Elyon) correspond to Nefesh, Ru'ach and Neshamah.
2.
Malbim: People pray at graves of Tzadikim.
