1)
Why is it written b'Nafsho, and we pronounce it b'Nafshi?
1.
Radak: The writing means that to kill him would be Sheker, for the king commanded not to. The pronunciation means that even if the king would not find out, I would not do Sheker myself, for I know that the king commanded!
2)
Why did he add "v'Chol Davar Lo Yikached
1.
Malbim: This is a second reason not to kill him.
3)
What is the meaning of "v'Atah Tisyatzev mi'Neged"?
1.
Radak: You would not save me from the king.