1)
Why did he ask Hashem to be a Dayan and Shofet?
1.
Malbim: Dayan refers to one who hears the claims of the litigants. Shofet refers to the final verdict according to Halachah. David said, Hashem should accept my claims against you, and judge between us according to Halachah.
2)
What is the meaning of "v'Yarev Es Rivi"?
1.
Malbim: He should claim for me.
