Why did she call him "Ish ha'Elokim"?
Mahari Kara: She thought that he is a man.
Malbim: She was unsure if he was a man or an angel. She said Ish, because he was dressed in a physical form. She said ha'Elokim because [his appearance] was fearsome like that of an angel.
Why did she say "k'Mar'e Mal'ach ha'Elokim Nora Me'od"?
Mahari Kara: If you want to ask him more about the child, a Siman of who it was is that his appearance was fearsome. However, I do not know his place or name.
Radak: The masses (including her) think that an angel is a [physical] body, and its form is awe-inspiring.
Malbim: Refer to 13:6:1:2.
Why did she say "I did not ask where he is from, and he did not tell me his name"?
Refer to 13:6:2:1.
Malbim: The custom was, one asks about another's place (residence), and he responds and tells his name, i.e. "va'Yomer Lo Michah me'Ayin Tavo va'Yomer Elav Levi Anochi" (17:9).