1)
Here it says "v'Lo Sham'u l'Koli." Verse 2 says "v'Lo Shematem b'Koli"!
1.
Malbim: Shemi'ah b'Kol' is accepting the commands or words themselves. Shemi'ah l'Kol' is accept the claim or proof intellectually, like (Yirmeyah 18:19) "u'Shma l'Kol Yerivai" (their claims) and (Yirmeyah 6:17) "Hakshivu l'Kol Shofar" (the Shofar hints to punishments).
