What is the meaning of "va'Yischapes"?
Rashi citing Targum Yonasan: He changed his garments. 1 The same applies to "Hischapes va'Vo ba'Milchamah" (Melachim 1 22:30), "b'Rav Ko'ach Yischapes Levushi" (Iyov 30:18).
Vayikra Rabah 26:7: He became Chafshi from kingship. Kli Yakar - his honor was lowered through this, and he was punished with death.
Kli Yakar: He sullied himself with sin. This is like changing from clean garments to dirty garments; we find that Yehoshua Kohen Gadol's garments were dirty due to his sons' sins (Zecharyah 3:4).
Who were the two men with him?
Radak citing Midrash Shmuel 24:2: They were Avner and Amasha.
Why does it say "Laylah"?
Rashi citing Tanchuma Emor 2: It was day, but amidst their affliction, it seemed to them like night. Kli Yakar - Chazal expounded so, for it does not say ba'Laylah.
Radak: It was at night, lest she recognize Sha'ul. Malbim - also, the king does not normally go out at night, and not with only two men with him.
Why did he say "Kasami Na Li b'Ov"?
Radak: Kosem is a general word for witchcraft. "B'Ov' specifies which kind.
Kli Yakar: Kasami? Li - can you tell me who I am? (He wanted to test if she is truly a Chacham about this.)
Why did he not immediately say that he wants to speak to Shmuel?
Kli Yakar: He wanted to test her Chachmah about this, if she can bring up the one he wants, after he whispers it and she does not hear the name.
Malbim: She would have sensed that he is not a commoner. A commoner would not be so bold to ask to conjure up a Navi!