What was Moshe's query?
Rashi #1 (citing R. Akiva): Moshe claimed that, however many animals Hashem would provide, it would never suffice 1 ("u'Matza lahem") for so many people for thirty consecutive days!
Rashi #2 (citing R. Shimon) 2 : Moshe was commenting that it was not in keeping with Hashem's dignity to provide them with so much meat and then to wipe out the entire nation! 3
Rashi #3 (in Pasuk 23, citing R. Gamliel ben R. Yehudah ha'Nasi) and Seforno: Seeing as Yisrael possessed plenty of cattle and they were only seeking an excuse to complain (or to test Hashem - Seforno), 4 irrespective of how much meat Hashem would provide them with, they would never be satisfied! 5
Ramban: If Hashem would gather all the sheep and cattle or all the fish that were available in that area, it would not suffice to feed the entire nation for thirty days. 6
Rashbam: With reference to Shechting their own animals, Moshe was pointing out that, in view of the size of the camp (six hundred thousand men, besides the women and the children), their sheep and cattle would never suffice to feed them all for thirty days! Consequenrly, either Hashem would have to kill many of them - so that there would be sufficient meat for those who remained or He would have to perform a miracle and bring meat from elsewhere. 7
Da'as Zekenim #1 (in Pasuk 21, citing Rav Nisim Gaon): Surely Hashem can supply enough for them to eat for a month, but how would they gather it all in one day? 8
Da'as Zekenim #2 (in Pasuk 23): They can eat Beheimos only as Shelamim. There are only three Kohanim. They will not be able to eat Chazah ve'Shok of all the animals and It will become Nosar. 9
Rosh and Moshav Zekenim: In the desert they could eat Beheimos only as Shelamim. Aharon and his [two] sons must bring the blood and Eimurim to the Mizbe'ach. (They cannot offer so many animals in one day.) How will this suffice for all of Yisrael?
Targum Yonasan: ?Even if one were to Shecht all the sheep in Arabia and all the cattle in Keidar 10 and one were to gatjher all the fish in the ocean, would it suffice for them??
Rashi: As in Vayikra 25:26 "u'Matza K'dei Ge'ulaso".
Rashi: Who maintained that Moshe, about whom the Torah will write (later, in 12:7) 'be'Chol Beisi Ne'eman Hu', would never have said what R. Akiva quoted him as saying!
Rashi: Because to do so would be comparable to offering a donkey a Kur of barley and then cutting off its head.
Rashi and Seforno: If He would give them cattle, they would claim that they wanted small animals, and vice-versa ... or deer's meat, or fowl, or fish or locusts. The Seforno adds that Hashem would have to remove their Bechirah (their freewill and choice), something that He does not do on principle, as the Gemara states in B'rachos, 33b.
Ramban: And Moshe figured that Hashem did not intend to perform a miracle and bring them from other locations - a. because whenever He did, the miracle was completely for the good (with Midas Rachamim) or completely bad (with Midas ha'Din) - which Moshe understood was not the case here; and b. because whenever He performed a miracle, He told Moshe in advance, clearly and unequivocally (See for example, Sh'mos 16:4 & 17:6), and not in vague term, as He did here (See Ramban).
Refer to the note in the previous answer.
Surely one animal suffices for a person to eat in one day. If one can gather one animal in twenty minutes, he can gather over thirty in one day? Perhaps Moshe thought that such a multitude of animals must be spread over a large area, and people will need more than twenty minutes to go out and gather each animal. (PF)
According to answers #7 & #8, what was Moshe?s question regarding fish?
See Na?ar Yonasan.
According to R. Akiva (that Moshe queried Hashem's ability to satisfy the people) why was Moshe not punished here in the same way as he was punished later when he said "Shim'u Na ha'Morim" (20:10), even though this sin was much worse?
Rashi: Because whereas Moshe declared "Shim'u Na ha'Morim!" publicly, 1 the current sin was said to Hashem in private conversation.
So Moshe was punished for the Chilul Hashem involved.
What are the implications of the word "Sheish Me?os Elef Ragli"?
Sotah, 12b: It implies 'Because of me' - Thanks to Moshe - whose birth stopped the decree (of "Kol ha'Ben ha'Yilod ha'Ye'orah Tashlichuhu!?) and saved the lives of all of Yisrael. 1
See Torah Temimah, note 19.
What is the significance of the fact that Moshe said ?Yishachet lahem" regarding the animals and "Ye'asef lahem" regarding the fish?
Chulin, 27b: To teach us that fish may be eaten as soon as they are caught, and do not require Shechitah. 1
See Torah Temimah, note 20.
QUESTIONS ON RASHI
Rashi writes that Moshe was punished for "Shim'u Na ha'Morim", whicht was said publicly more than for what he said here. But the Mishnah states in Avos, 4:4 that Hashem punishes soneone who sins in private publicly (more severely), than one who sins in public?