1)
What is the meaning of "Elokim Lehatzileni"?
1.
Radak: Rush to save me. The second half of the verse proves [about what is omitted in the first half]. Alternatively, there is no omission; "Chushah" applies to "Lehatzileni" and "l'Ezrasi".
2.
Malbim: Save me from those who come to kill me.
2)
Why does it say "Elokim" and also "Hashem"?
1.
Radak: Just like the matter is doubled, also calling out [to Hashem].
3)
What help does David request?
1.
Malbim: Help me from other Tzaros.