1)
Why does it say "Ki Alecha Nasasi Cherpah"?
1.
Radak: Due to You [I bear shame in Galus]. If I wanted to leave Your creed and adopt their creed, I would be great like one of them!
2.
Malbim: This is why Kovei Hashem will be shamed if You do not save me, for the shame that I bore was due to You.
2)
What is "Klimah"?
1.
Sha'arei Teshuvah 1:22: It is greater than Bushah (shame), therefore it is always mentioned after Bushah; the color of his face changes.
2.
Malbim: Refer to 69:7:2:2.