1)
From whom will the remnant be?
1.
Malbim: It will be also from Resha'im who do not recognize Hashem also in Galus (like those who went to Egypt and offered to Heavenly bodies ? Yirmeyah 44).
2)
Why will they discuss all the abominations?
1.
Rashi: They will say, we were stricken due to our sin, for we did such and such. I will make known that they were not eradicated without reason.
3)
Also the previous verse said "v'Yad'u Ki Ani Hashem." Why is this repeated?
1.
Malbim: Here it means that h Goyim will know that I am Hashem.