What is the mean of the question "Mi Manah Afar Ya'akov"?
Rashi #1 (citing Targum Onkelos) and Rashbam: 'Who can count the children 1 of the House of Ya'akov, 2 (about whom it was said that 'They will increase like the dust of the earth!'? - Targum Onkelos).
Rashi #2 (citing Tanchuma): 'Who can count the number of Mitzvos that they perform with earth - "Do not plow with an ox and a donkey"; 3 "Do not plant Kil'ayim"; 4 the ashes of the Parah Adumah; the earth used for Mei Sotah!'
Ramban: Refer to 23:9:2:3. The children of Ya'akov will always be uncountable like the dust of the earth.
Targum Yonasan: He said this in connection with the Mitzvah of B'ris Milah that Yisrael perform, after which they bury the Orlah (foreskin) in the desert sand. 5
See Ba'al ha'Turim. Rashbam (on Pasuk 9): 'And it is due to the children, who did not sin, that Hashem does not want to curse them, as we find in Yonah, 4:11, in connection with Ninveh.
Rashbam: Who were only counted from the age of twenty and onwards.
See also Ba'al ha'Turim.
What is the meaning of "u'Mispar es Rova Yisrael"?
Rashi #1: 'Who can count the total of one of the four camps of Yisrael!'
Rashi #2: 'Who can count the number of descendants that come from their acts of intimacy'? 1
Rashi #3 (24:3): 'Hashem sits and counts the seed of Yisrael to see when a Tzadik is born from it'.
Rashbam: 'Who can count the children of Yisrael?' 2
Targum Yonasan" 'or ... the good deeds performed by one of the four camps of Yisrael!'
What did Bil'am mean when he asked to die "Mos Yesharim u'Sehi Achrisi Kamohu"?
Rashi: He meant that he wished to die like the upright of Yisrael 1 [and his end will be like theirs. Da'as Zekenim, Hadar Zekenim
Rashi (Avodah-Zarah, 25a): To merit the death of Gevi'ah (expiry) like the Avos. See also Sifsei Chachamim, Ba'al ha'Turim. Lev Eliyahu (Shemos p.72)
And what did he mean when he concluded "u'Sehi Achrisi Kamohu"?