What is "Lechem Abirim"?
Rashi (from Yuma 75b) #1: Food that angels eat.
Rashi (from Yuma 75b) #2: Food that is absorbed in one's 248 limbs; people did not need to excrete waste.
Radak: It is food of (from) Shechakim, which are Abirim - it says about Shechakim "Chazakim ki'R'i Mutzak" (Iyov 37:18).
Malbim: The manna that descends naturally in the Midbar was not what healthy people eat to satiation. Rather, it is given to the ill. Hashem gave food proper for mighty people!
Who is the "Ish"?
Yuma 76a: It is Yehoshua. [As much] manna fell for him (while he was waiting for Moshe to descend from Sinai) as for all of Yisrael 1 .
Radak: It is any Yisrael - this is astounding, that one who [descends from Adam, who was] created from the ground, ate bread of Shechakim!
Malbim: It is every man. Refer to 78:25:3:2.
Rav Elyashiv (76a): Even though he could not eat it all (surely he ate only an Omer per day, like everyone else), so much fell for him for his honor, to show that he is equal to all of Yisrael.
What do we learn from "Tzeidah Shalach Lahem la'Sova"?
Radak: Wherever they went, provisions were prepared for them, to satiation.
Malbim: The manna that descends naturally in the Midbar is not satiating, and only a little descends. It could not suffice for 600,000 men. Here, every man ate to satiation, which is impossible with the natural manna.