1)
Why does he bless Hashem?
1.
Radak: He thanks Hashem for teaching to him.
2.
Malbim: Above (5), he said "Achalai Yikonu Derachai Lishmor Chukecha". Now he says that Hashem already accepted his Tefilah; he guards Hashem's Chukim, and blesses Him for this.
2)
Why does it say "Lamedeni Chukecha"?
1.
Radak: He requests that Hashem teach to him more.
2.
Malbim: He requests that Hashem teach to him the inner content and secrets of the Chukim, in the way of learning.
