What is "Adiro"?
Rashi: Its officer.
Radak: Its king. "U'Moshlo" is a repetition in a different word. It was known that Mashi'ach will be from Yisrael. The Chidush is, Yisrael will not have any Nochri rulers like they had in exile. And even in Eretz Yisrael, sometimes they paid taxes to kings of other nations. This will cease!
Why does it say "mi'Kirbo"?
Radak: This is like it says "mi'Kerev Achecha Tasim Alecha Melech 1 " (Devarim 17:16).
Malbim: Yisrael will choose their own leaders - unlike in Bayis Sheni, when other nations that ruled over Yisrael picked the leaders.
Yevamos 45b: All appointments of authority must be "mi'Kerev Achecha", i.e. his mother must be Jewish.
To whom does "v'Hikravtiv v'Nigash Elai" apply?
Radak: It applies to the king - "Ani Ehyeh Lo l'Av v'Hu Yihyeh Li l'Ven" (Shmuel II, 7:14).
Radak citing Targum Yonasan: It applies to Yisrael - I will draw them close, and gather them to My service.
Malbim: I will bring him to be one of those close to Hashem who stand in His Heichal - "Ashrei Tivchar u'Skarev" (Tehilim 65:5), "Hashem separated you (Shevet Levi) from Adas Yisrael to bring you close to Him" (Bamidbar 16:9). Hashem will choose one man to be a Segulah to Him, like [He chose] Shevet Levi, the seed of Aharon and David.
What is the meaning of "Arav Es Libo"?
Rashi: He accepted to be a guarantor.
Radak: He improved his heart and made it proper to approach Me. (Anyone who did so, I drew him close, even among the nations, and all the more so among Yisrael, who are My close ones from of old!)
It is to be presumptuous. (PF; it seems that Malbim explains so. He says, no one would approach Me on his own.)
What is the meaning of "Lageshes Elai"?
Rashi: To make war, to protect against Me.
Radak: Refer to 30:21:4:2.