1)
Why does it say "Lachen"?
1.
Malbim: Hashem accepted the envy of the trees of Eden (refer to 31:9:2:2).
2)
To whom did Hashem say this?
1.
Rashi: To Ashur.
3)
What is the significance of "Gavahta b'Komah va'Yiten Tzamarto El Bein Avosim"?
1.
Malbim: I will punish due to the pride of Melech Ashur, (a) over his strength, (b) he thought that his strength is from himself, and he put his top among Avosim - "b'Cho'ach Yadi Asisi" (Yeshayah 10:13).
4)
It says "Gavahta" (second person), and "Tzamarto" (third person)!
1.
Radak: Verses often switch between them, e.g. "Shim'u Amim Kulam" (Melachim I, 22:28).