1)
What is the significance of the fact that the angel told Lot that he was unable to overturn S'dom until Lot arrived at his destination?
1.
Rashi: This was a punishment for having previously declared that they were going to destroy S'dom instead of attributing it to Hashem. 1
1
Or because they revealed to Lot Hashem's secret - that he was about to overturn S'dom, Refer to 28:12;1:6.
2)
Why did the angel speak in the singular?