On what basis was Aharon Moshe's interpreter?
Tosefta, Megilah: Because Aharon was Moshe's junior; 1 and it is appropriate for a junior to act as the interpreter of his senior, but not vice-versa.
Albeit not in terms of age, but in many other aspects. See Torah Temimah, 6:27, note 19.
What is the meaning of, "Nesati'cha Elokim l'Pharaoh"?
Rashi: 'I made you a judge and a ruler over Pharaoh' - to strike him with punishments and suffering. 1
Targum Onkelos: 'I have made you a master over Pharaoh.' 2
Targum Yonasan: 'I have placed your fear into Pharaoh, as if you were his god.'
Hadar Zekenim #1, Da'as Zekenim: You are like G-d to Pharaoh.' 3
Hadar Zekenim #2 (to 12:12): 'Elohim' here means a great person, as in "uv'Chol Elohei Mitzrayim E'eseh Shefatim" (12:12). 4
But "Aharon will be your Navi" implies that 'Elokim' has some connection to Divinity? (PF).
Compare to the verse "and you shall be for him (i.e. Aharon) as Elokim" (4:16); refer to 4:16:1 and to 7:1:151.1:1.
Because Pharaoh made himself a god, and said, "The river is mine, and I made myself" (Yechezkel 29:3). Hadar Zekenim - Hashem said to Moshe, 'Do not behave haughtily towards the people - because I made you a god only to Pharaoh.'
QUESTIONS ON RASHI
Rashi writes: "I have made you an Elohim to Pharaoh - A judge and punisher, to afflict him with plagues and suffering." What are the implications of this term?
Maharal (Gevuros Hashem Ch. 28, p. 113): The name Elokim indicates Midas ha'Din (as it does when referring to Hashem). Compare to Shemos 4:16 - Aharon would be Moshe's mouthpiece (i.e. spokesman), while Moshe would be his "Elohim" (i.e. officer, master) (Rashi ibid). 1
And Moshe should therefore be the Levi (and not the Kohen - see 4:14:1.2). The tribe of Levi is associated with Midas ha'Din - Refer to Bereishis 49:5:1:7, and to Bereishis 49:5:2.1:1.
Rashi writes: "[Aharon] will be your Navi - ... the term 'Nevu'ah' means 'to announce, to proclaim' ... as in the verse 'Niv Sefasayim' (speech of the lips) (Yeshayahu 57:19)." Ibn Ezra asks - But these are different words! The Shoresh (root) of the word 'Navi' is Nun-Beis-Alef, whereas the root of 'Niv' is Nun-Yud Beis.
Gur Aryeh: Rashi's approach is that even if the [three-letter-] roots are not completely identical, we may compare them to derive a meaning. When one of the roots' letters at times falls away, 1 so long as the essential letters of the word are the same, the meaning will be very similar. 2
Gur Aryeh: For example, when the first letter of a root is Yud, or when its middle letter is Vav, or if the second and third are the same letter doubled. (In our case, the last letter of the Shoresh is an Alef, which sometimes disappears, as in the verse (Shmuel I 10:13) that Rashi cites. Only two letters of these roots are significant letters -- Nun-Beis.) Gur Aryeh also cites Mizrachi's answer, from which he differs. Also see Bereishis 49:17:1.1:1.
This approach using two-letter roots is used by Menachem ibn Saruk (often cited by Rashi); and later more extensively by Rav Shlomo Poppenheim (often cited by the work Ha'Kesav Veha'Kabalah). (Interestingly, Rav Poppenheim lists the word "Navi" under a different root, Beis-Alef (to come, to bring). The Navi's task is to inform us of events to come, and to bring Hashem's message to us - (CS, and see Yalkut ha'Shorashim (Steinberg)).)
Rashi writes: "... The term 'Nevu'ah' means 'to announce, to proclaim' ...." Ibn Ezra asks - How will Rashi explain the verse, "Return the man's wife, for he is a Navi" (Bereishis 20:7) - Is that the reason he must return her?
Gur Aryeh: The term Navi specifically refers (not to just any town crier, but) to one who proclaims the word of Hashem. Only Hashem's word is hidden from the public, and needs someone to proclaim it. 1 Hashem told Avimelech, 'You must return his wife, for he proclaims the word of Hashem; and he is able to punish you if you don't!' 2
Gur Aryeh: But in our Pasuk, "Navi" is a borrowed term (or a metaphor). Aharon would be Moshe's spokesman in general - not limited to the words of Hashem.
Rashi to Bereishis 20:7 gives a different explanation.
