1)
Why does it say "k'Chol ha'Devarim ha'Eleh uch'Chol ha'Chizayon"?
1.
Kli Yakar: This refers to the harsh matters and the good matters. Devarim can refer to harsh matters, e.g. "Diber ha'Ish Adoni ha'Aretz Itanu Kashos" (Bereishis 42:30). Or, Chizayon can refer to harsh matters - "Masa Gei Chizayon" (Yeshayah 22:1).
2.
Malbim: The first half of these words, until "v'Asisi Lecha k'Shem ha'Gedolim", was rebuke - k'Chol ha'Devarim. The second half was prophecy for the future - uch'Chol ha'Chizayon. Nasan was not ashamed to say also the rebuke, like it was said to him.