What exactly does "Mirkeves ha'Mishneh" mean?
Rashi: The chariot that was second to his own (Pharaoh's).
Ramban: The chariot that the king designated for the one who was second to the king. 1
Rashbam: On the horse or mule that was designated for the one who was second to the king.
Tosfos ha'Shalem (1, citing Hadar Zekenim): Initially, there was only one horse in the chariot. Yosef enacted a second. 2
See Ramban.
Hadar Zekenim: Pharaoh added a third when he chased Bnei Yisrael - "v'Shalishim Al Kulo" (Shemos 14:7). Shlomo raised it to four - "a chariot for 600 silver pieces, and a horse for 150" (Melachim I 10:29).
What is the meaning of "Avrech"?
Rashi #1, Rashbam, Targum Onkelos and Targum Yonasan: 'This is the father of the king' 1 (viceroy)!"
Rashi #2 (citing the Sifrei): 'A father in wisdom, young in years!'
Rashi #3 and Seforno: It means, 'Kneel!' 2
Hadar Zekenim citing Ibn Ezra: Everyone says to him, 'I will bend my knees to you.'
Ha'amek Davar: It is a father of authority. All authorities in Egypt will be under him.
Reich(a) is the Aramaic word for king, as in Bava Basra 4a (see Rashbam loc. cit). See also Bereishis 45:40.
Rashi: "Avrech" is a derivative of 'Birkayim' (knees).
Why does it say "v'Nason Oso..."?
Ohr ha'Chayim: "Va'Yikre'u" applies to also to this. Everyone said both Avrech and v'Nason Oso..., to publicize that he rules over Egypt like a king.
Ha'amek Davar: Initially, Yosef ruled only over the capital; now he is over all of Egypt.
QUESTIONS ON RASHI
Rashi writes: "'Mirkeves ha'Mishneh' - Second (in distinction) to his own chariot." How else might I have interpreted this?
Gur Aryeh: I might have interpreted as 'the double chariot;' as in "Kesef Mishneh" (43:12) which means "double the money." But why would it be a sign of distinction to ride upon a double chariot? Yosef's distinction was to ride in second position, adjacent to the king.
