1)
Why did he say "Im Akaveh She'ol Beisi"?
1.
Rashi: "Im" means since, like "Im Charutzim Yamav 1 ." Since I hope [to die, and] the grave will be my house...
1
So Seforno explained there (14:5), but Rashi did not! (PF)
2)
What is the meaning of "ba'Choshech Ripadti Yetzu'ai"?
1.
Rashi: I spread my bed-sheet in the grave.
2.
Malbim: I hope to lie in darkness.
