Why is Moshe discussing specifically the Chukim and the Mishpatim?
Ramban: After issuing a warning about the Mitzvos in general
By referring to the episode of Ba'al Pe'or.
It is not clear however, how this applies to Chukim, about which Chazal state that the Satan and the nations of the world take Yisrael to task (See Rashi, Bamidbar, 19:2)?
As the ensuing Pesukim go on to explain.
What are the implications of the word "Ka'asher" (instead of 'Asher') in this Pasuk?
Bechoros, 29a: It implies
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"?
Ramban: Either because many of the Mitzvos only apply in Eretz Yisrael, or because basically all the Mitzvos are meant to be kept in Eretz Yisrael.