1)
What is the meaning of "k'Tzel ki'Ntoso"?
1.
Rashi: Like a shadow leans towards evening.
2.
Radak: Just like shade leans quickly, so I leaned and went. I.e. my days went quickly, without desire.
3.
Malbim: When the evening shadows lean, the day will set soon. So I went, for I am close to death.
2)
What is the meaning of "Nin'arti ka'Arbeh"?
1.
Rashi: It is an expression of pain, anxiety, like locusts, that go madly to and fro. Radak - locusts have no nest; they go from fence to fence. So I have no secure dwelling in one place, for when Sha'ul knows that I am in a place, he chases me, and I flee from place to place.
2.
Malbim: Just like the wind blows locusts from place to place, so I roam.