1)
Why does he say "Lema'an Shimcha"?
1.
Radak: In order that Your name will be aggrandized in the mouth of people, when You will save me and revive me from my great affliction, in which I am close to death.
2.
Malbim: I request that You keep me alive for the sake of Your name.
2)
What does "Totzi mi'Tzarah Nafshi" add?
1.
Malbim: Take me out of the cave, and show to me where to go.