What blood will He remove, and from whose mouth?
Rashi #1: This refers to Beis Bimah of Esav, from which they threw blood of Korbanos.
Rashi #2: [Esav] used to spill blood of Yisrael.
Radak: This is a Mashal - what [Pelishtim] consumed Yisrael is his blood and abomination. I.e. I will eradicate those of evil hearts from among them.
Radak citing his father: It is foul language that Nochrim are used to.
Malbim: I explained in Amos 1 that it is the blood of Yisrael that [Pelishtim] spilled.
What is "Shikutzav"?
Malbim: His idolatry.
What will remain for Elokeinu?
Rashi: Batei Kenesiyos and Batei Midrash in their Galus.
Radak: After I eradicate the Resha'im among them, those who remain, their hearts will be proper to Hashem.
Malbim: Just like Damesek and Tzor will be of Yisrael, also the places of Pelishtim.
What will be "k'Aluf bi'Yhudah"?
Rashi: Their theaters and meeting places. In the future, officers of Yehudah will teach Torah there in public (Megilah 6a). Aluf is an expression of teaching.
Radak: Those who remain will be like other "u'Vnei ha'Nechar ha'Nilvim Al Hashem", about whom it says "va'Havi'osim El Har Kodshi v'Simachtim b'Veis Tefilasi" (Yeshayah 56:6-7). They are like chiefs and great people of Yehudah! It mentions Yehudah, for there is Har ha'Kodesh and Beis ha'Tefilah.
Malbim: The places of Pelishtim will belong to Shevet Yehudah, and they will be among the big cities where they learn Torah.
What is the meaning of "v'Ekron ki'Yvusi"?
Rashi: Ekron will be to Yisrael like Yerushalayim is.
Radak: Ekron will be like Yevusi, who dwell in Yerushalayim amidst Bnei Yisrael, and they serve Yisrael and pay taxes. So it will be in the days of Mashi'ach.
Malbim: Yevusi dwelled in Yerushalayim, and then it became Ir ha'Elokim. So Ekron will be Kodesh la'Shem!