What are implications of the word "Navi mi'Kirb'cha"?
Ramban #1: It implies that Nevu'ah is restricted to Eretz Yisrael. 1
Ramban #2: It implies A Navi whose words you can trust because he is one of you.
Ramban: As the Pasuk hints in Yeshayah, 22:1. See also Torah Temimah, note 68.
What are the connotations of the word "mi'Kirb'cha me'Achecha Kamoni"?
Rashi: Just as I am from among you, from your brethren, 1 so will Hashem set up for you in my place, and so from Navi to Navi.
Ramban (citing the Ibn Ezra) and Rashbam #1: A Navi Hashem like Moshe 2 - and not a Me'onein or a Koseim (a false Navi or a dreamer 3 ? Rashbam).
Ramban: Refer to 18:15:1:2. And a Navi who is reliable as a Navi of Hashem and in whom you will trust 'just as you trusted me'.
Rashbam #2: Refer to 18:18:1:2 and note.
Targum Yonasan: Someone who has Ru'ach ha'Kodesh like Moshe. 4
Sifri: "mi'Kirb'cha" confines Nevu'ah to Eretz Yisrael, 5 and "me'Achecha" precludes accepting prophecies from Nochrim.
Rashi (Sanhedrin 39b): Normally, the Shechinah rests only on Yisre'elim of pure lineage. The only convert to become a Navi was Ovadyah, a Ger Edomi - a merit that he earned on account of the outstanding deed that he performed Mesiras Nefesh to sustain a hundred prophets when Izevel was killing them - see Sanhedrin, 39b. (According to Kabalah, the prophecy about the downfall of Edom needed to come from an Edomi (heard from R. Meir Eliyahu). Efrayim Maksha'ah in Sanhedrin, Ibid. supports this).
Rashbam: Who will teach them the Mitzvos of the Torah like Moshe - See Rashbam.
Rashbam: Who will instruct them to worship idols.68.
See Peirush Yonasan.
See Torah Temimah, note
Why does the Torah add the word "Yakim l'cha Hashem Elokecha"?
Rashi (in Yirmiyah, 1:5, citing the Sifri): To preclude a Navi prophesying on behalf of Nochrim. 1
Rashi (Ibid.): And when Hashem said to Yeshayah "Navi la'Goyim Nesaticha", He meant for Yisrael who were behaving like Nochrim'.
Why does the Torah add the (otherwise superfluous) words "Eilav Tishma'un"?
Seforno: To obligate listening to a Navi even if he issues a one-time command to transgress a Mitzvah from the Torah (like Eliyahu on Har ha'Carmel, who ordered the construction of a Bamah at a time when Bamos were forbidden - Yevamos 90b). 1