Why does it mention Bushah and Kelimah?
Radak: Kelimah is greater than Bushah.
Malbim: Bushah is feeling ashamed by himself. Kelimah is from others. When one makes himself submissive to a lowly person in order that he will save him, and he truly saves him, he is ashamed from others, for he lowered himself to a disgraced person. He is not ashamed by himself, for he received the salvation from him that he hoped for. When one makes himself submissive to an honored person so that he will save him, and he does not save him, he is ashamed by himself, for he did not get his request, but he is not ashamed from others. When one lowers himself in front of a lowly person, and he does not fulfill his request, he is ashamed himself and also from others. This applies to those who bowed to the despised idol.
Why does it say "Halchu"?
Malbim: They will have this shame forever.
Who are "Charashei Tzirim"?
Rashi: They are craftsmen. Radak - idols are called Tzirim. This is like "Tzirim va'Chavalim Yochezun" (13:8; contractions and birth-pangs). They and the worshippers will be ashamed, for the idols did not save them at the time of their affliction.
