1)
What is the significance of calling Him "Avi"?
1.
Radak: He will cling to Me, and know that help comes to him from Me.
2.
Malbim: His connection to Hashem is like one who needs for happiness (a) a father fathered him and brought him into existence; the son receives bodily powers from him, and his father guards him until he is a man; (b) his teacher; his king who teaches him happiness of the Nefesh, Torah, Chachmah and Emunah. The king saves him in running the country, and makes him an officer.
2)
What is the significance of calling Him "Keli v'Tzur Yeshu'asi"?
1.
Malbim: Keli shows Emunah in Kel; Tzur Yeshu'asi - He saves him from every Tzarah (affliction).
