What is the meaning of "Bi Hashem"?
Radak: The word is Chulin (it does not refer to Hashem). He did not know that an angel spoke to him (until verse 22); in verse 13 it says "Adoni" with a Chirik under the Nun. Here it has a Kamatz due to the [note] Zakef. 1 Normally, Adon is plural, e.g. "Adonecha" (Melachim 1 18:8), "Adonav" (Mal'achi 1:6), except when speaking to the person, lest it be confused with Hashem's name. This is the only exception.
Radak citing Targum Yonasan: Gid'on said so to Hashem. (He did not know yet that an angel spoke to him. 2 )
Otherwise, it would be a Patach. When Lot addressed the angels, he said with a Patach (Bereishis 19:2). Ibn Ezra says (unlike Shevu'os 35b) that even in 19:18 it is Chulin, it has a Kamatz because it is Sof Pasuk. Radak did not explain why verse 13 is singular (Chirik), and here plural (Patach, and it changed to Kamatz. - PF)
Until verse 22. Before, he must have thought that he is a Navi. How else could he command him to save Yisrael? And if not, why would Gid'on speak to Hashem and expect an answer? (PF)
Why did he ask how he will save Yisrael?
Malbim: He thought that the salvation will be via natural means, because the command came through an angel "Hinei Anochi Shole'ach Mal'ach Lefanecha" (Shemos 232:20).
What is the meaning of "Alfi ha'Dal bi'Menasheh"?
Rashi: The 1000 over which I am (Radak - my father's house is) appointed is the weakest in Menasheh.
Radak citing Targum Yonasan: My seed.
Radak: My father. This is like Aluf (Bereishis 36:15), which means a chief or master.
Malbim: He thought that the salvation will be via natural means. It will not be through multitudes, for Alfi ha'Dal. And Yisrael will not heed me, for I am the youngest in my father's house!
