Why is Moshe discussing specifically the Chukim and the Mishpatim?
Ramban: After issuing a warning about the Mitzvos in general - represented by the La'av of Avodah-Zarah, 1 Moshe warns the people about the Chukim - Hashem's decrees, and Mishpatim - the civil laws, which require special attention, the former, because their reasoning behind them is unknown; the latter, because 'the land continues to exist (only) upon justice'. Moreover, Moshe is pointing out to them the special qualities of the Chukim and Mishpatim, in that a. they glorify those who observe them and that even their enemies praise them (Yisrael) on account of them, 2 b. they posses the incredible benefit that, because of them, Hashem answers them whenever they call out to Him and c. they are intrinsically righteous and good, for the survival of the people and the community at large. 3
What are the implications of the word "Ka'asher" (instead of 'Asher') in this Pasuk?
Bechoros, 29a: It implies 1 that, just as Hashem taught Moshe free of charge, so too should one teach one's Talmidim free of charge.
See also Torah Temimah.
Why did Moshe add "La'asos kein be'Kerev ha'Aretz"?