1)
Why does it say "Shim'u Musar va'Chachamu"?
1.
Malbim: This corresponds to "Atah Vanim Shim'u Li" (32). It is hard to accept the laws of Chachmah, for Da'as has no proof for them. It is hard to guard them, for the Yetzer ha'Ra of the heart opposes them. Hearing Musar (Musar Chachmah), which is Yir'as Hashem, fixes this. Fear restrains the powers of the Nefesh to accept the laws of Chachmah (1:2); via this, you will become Chachamim.
2)
What is the meaning of "v'Al Tifra'u"?
1.
Rashi: Do not nullify my Musar. Malbim - this corresponds to "Ashrei Derachai Yishmoru" (32).
