Why does it mention separately "Kol Sason" and "Kol Chasan v'Kol Kalah"?
Malbim: "Kol Sason" is only at a time of good and success. "Kol Chasan v'Kol Kalah" is even not at a time of good and success. As long as the land is settled, there will be marriages.
What are the significances of the sound of a mill and the light of a lamp?
Rashi (from Sanhedrin 32b): They are signs of Seudas Bris Milah (they grind ingredients to cure the wound) and of a drinking party, respectively.
Radak: They are signs of a Seudah of Simchah (they grind spices) and of a drinking party, respectively.
Radak citing Targum Yonasan: It is the sound of a group praising with light of a lamp.
Malbim: Even when the land is desolate and few people are in it for Kormim and Yogvim they will need mills to process food and lamps for residences. [If these are lacking, this shows that] the land is totally desolate.
