Why did she say "ha'Ovos" '(plural) and "ha'Yid'oni" (singular)?
Kli Yakar: There are two kinds of Ovos - without a Kli, and with a Kli (a human skull, or a crystal skull). There is only one kind of Yid'oni.
What is the meaning of "Misnakesh b'Nafshi"?
Rashi: You seek to make me stumble in sin. V'Lo Od Ela (33) - she was righteous, and feared only for the Aveirah.
Radak: You seek to make me stumble, in order to kill me.
Why did she say "Sha'ul" without a title of respect, and also in verse 12, when she knows that she speaks to him?
Before Sha'ul became king, he honored her, for a Chacham's wife is like a Chacham (Shevu'os 30b). She was Tzefanyah's wife (before or after she married Sha'ul's uncle Ner (14:50), for she was Avner's mother; refer to 28:7:4:1). Perhaps she continued to call him just Sha'ul even after he became king. (PF)