1)
Why did he say "Chalilah" twice?
1.
Rashi: Heaven forbid that I [would do so]. Heaven forbid that the king [would command to do so]!
2)
What is the difference between "Avala" and "Aschis"?
1.
Malbim: Hashchasah is even a small destruction, to ruin its walls and buildings. (Avala is total destruction.)