1)
Why did he say "ha'Yesupar ba'Kever Chasdecha"?
1.
Rashi: If we will die in the hands of our enemies, can we tell Your praise in the grave?!
2.
Radak: The matter is repeated again to strengthen it.
3.
Malbim: Even if You would do a miracle for the dead, the purpose of wonders is (a) that people will know that You did the wonders for them, and (b) so they can tell the wonders to others, so others will know Your Chesed and Emes. Even if the dead would know wonders that You do for them, they cannot tell others!
2)
What is "ba'Avadon"?
1.
Radak: It is the grave, in which the body is lost and perishes.
