Why does the Torah add the word "Nafesh" - which it did not do in Bereishis 46:27?
Oznayim la'Torah: To stress the fact that, not only did they retain their Jewish names, 1 but that they also retained their chastity - that all their children were descendants of Yaakov Avinu. 2 These were two of the four reasons that Yisrael merited redemption from Egypt.
Oznayim la'Torah: Since not one of them was born from an Egyptian mother. As matter of fact, all six hundred thousand people that left Egypt, were descendants of Yaakov Avinu. And the only one whose father was an Egyptian was the son of Shelomis bas Divri, see Vayikra 24:10.
Why aren't all of the seventy souls listed here by name (as they are in Bereishis 46)?
Maharal (Gevuros Hashem, beg. Ch. 13): The Shevatim are listed by name due to their importance; whereas the 70 descendants are only noted generally. 1
On a conceptual level, why did Bnei Yisrael descend to Mitzrayim specifically when they reached the number 70?
Maharal #1 (Gevuros Hashem Ch. 9, p. 54): With the number 70, they had a point in common with the 70 nations. Only now that they were in opposition, was it possible to become subjugated to Mitzrayim. 1
Maharal #2 (Gevuros Hashem, Hilchos Yayin Nesech, p. 333): See above, 1:5:1.02:1. Had the number of 70 2 been completed prior to their entry into Mitzrayim, Am Yisrael would have had their initial start even before their sojourn there. Had they reached 70 only after their entry, that would mean that Bnei Yisrael became subjugated before the proper time. Thus, Yocheved was born precisely as they entered the walls of Mitzrayim. 3
Maharal (ibid., end Ch. 11) expands upon this.
Maharal (loc. cit.): 70 is the Gematriya of "Sod" - secret. Although Yisrael reflects the 70 nations outwardly, they are distinct in their origin, and in their inner essence.
Rashi to Bereishis 46:15.
Seeing as Yosef was listed among the seventy souls who came down to Egypt, why does the Torah find it necessary to mention that Yosef was in Egypt?
Rashi: It wants to point out his Tzidkus, inasmuch as, despite the fact he was the same Yosef who tended to his father's sheep as the Yosef who lived for many years in (the depraved society of) Egypt, and that he even became 'king' there, he remained untainted.
Why was it specifically Yosef who descended to Mitzrayim ahead of his brethren?
Maharal (Gevuros Hashem Ch. 11, p. 62): The Egyptians were basely materialistic (Chomer); and were steeped in sexual immorality. Yosef, by contrast, was holy, separated from any such misconduct (see Bereishis 39). Just as Tzurah by definition rules over the Chomer, 1 it was fitting that Yosef descend to rule over Mitzrayim.
A materialistic person has no particular goal that guides his conduct; he is driven only by opportunity and lust. When a person of stature (Tzurah) takes charge, he gives his subjects purpose and helps them to actualize their potential. This is what Yosef did for Mitzrayim. (EK)
QUESTIONS ON RASHI
Rashi writes: "'And Yosef was in Egypt' - [Rashi asks,] but both Yosef and his sons are included in the count of 70... and do we not already know that Yosef was in Mitzrayim?!" What is Rashi asking here?
Gur Aryeh: a. Do not say it comes to exclude Yosef; we see in Bereishis 46 that Yosef is included in the count of 70; b. Do not say that on the contrary, it tells us to include Yosef; for then it should mention his sons as well! c. Do not take the verse in its simple sense, that Yosef preceded the rest of Bnei Yisrael to Mitzrayim, for we already know this! [Rather, we should interpret it as telling us that Yosef remained a Tzadik.]
