1)
Why does it say "Ish Al Re'ehu"?
1.
Radak: This is like Ish Al Re'ehu. Also "va'Yelech Elkanah ha'Ramasah Al Beiso" (Shmuel I, 2:11) is like El Beiso.
2)
What is the meaning of "Mah Anah Hashem"?
1.
Radak: This is like Mah Diber Hashem 1 . The same applies to "v'Anisa v'Amarta" (Devarim 26:5) and the first "va'Ya'an Iyov" (Iyov 3:2).
2.
Malbim: This refers to Hashem's answer to a Navi's question. "Mah Diber Hashem" (written after this) applies when Hashem began the Dibur.
1
Even though those are the next words in the verse, Radak holds that verses often repeat matters in different words to strengthen the matter. (PF)