1)
Why does it say "Lintzor Archos Mishpat"?
1.
Rashi: Via Chachmah, they will guard the ways of Mishpat.
2.
Malbim: This corresponds to "Yitzpon la'Ysharim Toshiyah" (7). The straight guard the ways of Hashem's conduct according to Mishpat, e.g. the acts in Egypt to strike the Egyptians and take out Yisrael. They were according to Hashem's Mishpat, reward and punishment. He summonsed the straight in the generation (Moshe and Aharon) to be the agents of His Hashgachah.
2)
What is the significance of "v'Derech Chasidav Yishmor"?
1.
Rashi: Via Chachmah, they will not stumble.
2.
Malbim: Refer to 2:7:2:2.
