1)
Why did he say "u'Leshoni"?
1.
Radak: They praise Hashem for what He did for me - all the more so, my mouth should speak Your virtue!
2)
Why does it say "Kol ha'Yom"?
1.
Radak: This is like they constantly say Your praise (verse 27).
3)
What are "Tzidkecha" and Tehilasecha"?
1.
Malbim: They are Your punishment of Resha'im, and reward for and guarding of Tzadikim, respectively.
