1)
Why does the Torah use the double expression "Ha'alem Ya'alimu"?
1.
Rashi: If they hide their eyes from one thing, they will eventually hide their eyes from other things; If the Sanhedrei Ketanah hide their eyes, ultimately the Sanhedrei Gedolah will hide their eyes, too. 1
2.
Oznayim la'Torah: It implies that the people not only turn a blind eye to the goings-on, but they also prevent the Beis-Din from taking action - a sure sign that Molech has caught on to the people, and explains why Hashem will punish, not only the sinner, but his entire family. 2
2)
Why does the Torah insert the (otherwise superfluous) phrase "be'Sito mi'Zar'o la'Molech"