What day is this?
Radak: It is the day of salvation.
Malbim: It is the day mentioned above (1-2). Verses 3-7 are the song about the vineyard, and 7-12 are a Ma'amar Musgar (parenthetical comment).
What is "Yachbot Hashem"?
Rashi citing Targum Yonasan: He will make fall dead.
Rashi: The two expressions Chibut and Lekitah (in this verse) are connected; one bangs olives off the tree and collects them, and others collect from the ground. So Hashem will begin the gathering - "Yitaka b'Shofar Gadol" (13).
Radak: Like one bangs wheat from straw, and olives from the tree, so Hashem will beat Yisrael from the nations. They are among the nations like wheat amidst straw and olives among olives trees. One gathers the good, i.e. the fruits, and leaves the straw and wood.
Malbim: Yisrael are compared to grain. The Nochrim among whom they are exiled are compared to straw and chaff. When Hashem wants to gather the cast off of Yisrael, first He will need to separate them from the Nochrim among whom they are mixed. This is like grain, which is mixed with chaff. This is compared to one who bangs grain, and via this the grain comes out, and the wind takes the chaff, So He will separate Yisrael, and the Nochrim will be wiped out like chaff is dispersed from the granary.
Who will come from "Shiboles ha'Nahar"?
Rashi: "Ha'Ovedim b'Eretz Ashur" (13). Radak - Shiboles ha'Nahar is where it flows rapidly. This is like "v'Shiboles Shetafasni" (Tehilim 69:3).
Malbim: This is where Hashem will separate Yisrael from the nations. Shiboles ha'Nahar is in Ashur.
Which river is this?
Rashi: It is the Pras; Bnei Ashur dwell near it.
Radak: It is the Sambatiyon river, like it says about the Shevatim "v'Zerem me'Ever la'Nahar" (Melachim I, 14:15).
Why does it say "Ad Nachal Mitzrayim"?
Rashi: This refers to "veha'Nidachim b'Eretz Mitzrayim" (13). Hashem will bang them like one bangs olives.
Radak #1: They will come until Egypt, and gather there with their brothers in this Galus, and ascend to Yerushalayim.
Radak #2: Egypt is the end of the kingdoms. The king of the north will fight the king of the south, and the former will come until Egypt and rule over all the hidden treasures of gold and silver and valuables, like it says "uva'Es ha'Hi Ya'amod Micha'el ha'Sar ha'Gadol ha'Omed Al Bnei Amecha" (Daniel 12:1).
Malbim: Yisrael were captive there, like it says in verse 13.
Who is "Atem", and from where will they be gathered?
Rashi: It is Yisrael; they will be gathered from Galus.
Radak: It is Bnei Galus, i.e. Yehudah and Binyamin, who are scattered in every corner. Therefore, it says that all of you on the other side [of the river] will be gathered.
Why does it say "l'Achad Echad"?
Rashi: One who finds one of you (Yisrael) will bring him for a Minchah (gift).
Radak: This is like it says "v'Lakachti Eschem Echad me'Ir u'Shenayim mi'Mishpachah v'Haveisem Eschem Tziyon" (Yirmeyah 3:14). One from here and one from here will gather.
Malbim: After the Nochrim are wiped out, Yisrael are scattered; each family will join.
