Why did Hashem say "Lachen"?
Radak: Those who do not want to repent - I inform them that this time, I will make My hand known.
Malbim: I do not envy idolatry, which is nothingness. Rather, it is because they choose something empty and deny Me, I want to punish them.
Whom is Hashem informing now?
Malbim #1: In the future, even Goyim will recognize My honor. Therefore, I want to inform Yisrael, that they will immediately know and recognize Hashem's strength and kingship.
Malbim #2: I now inform all the nations. Since He will bring Nebuchadnetzar against all of them, they should all recognize Hashem's strength; I punish Yehudah because "Chatas Yehudah Kesuvah b'Et Barzel" (17:1).
What is "Es Yadi v'Es Gevurasi"?
Malbim: I run and oversee [everything], and I can change the Ma'arachah as I desire.
What is the significance of "Shmi Hashem"?
Rashi: I have power to fulfill My decree.
Radak: This is like Ani Hashem. He is His name, and His name is Him.