1)
Why does it say that their sins are borne and covered?
1.
Radak: Refer to 32:1:3:3.
2.
Malbim: This is the third way that Hashem was appeased with His nation - He pardoned and bore their sin. This implies that the sin still exists, just Hashem bears it. In the final Ge'ulah, Hashem will eradicate their sins from existence.