1)
Why does it say "l'Galuseinu"?
1.
Rashi: It is from the Galus of Yehoyachin ? also Yechezkel was exiled then.
2)
Did Yechezkel not know that the Churban came until the Palit arrived five months later?
1.
Rashi, Radak (24:26): Correct. Refer to 24:26:1:1-2, 24:26:1:2*.
2.
Malbim: Yechezkel saw prophetically on the day of the Churban. When the Palit came later, he heard physically.