Who is the angel who redeemed Ya'akov from all his troubles?
Rashi, Targum Onkelos and Targum Yonasan: The angel that always redeemed him in times of trouble. 1
Ramban (Sh'mos 23:20): It is the Angel Matatron, whose Name is equivalent to that of his Master. 2
Moshav Zekenim (15): In the Sod of the Merkavah, Hashem is an angel in the Sod of angels, He is Galgal (the sphere on which the Mazalos) are fixed in the Sod of Galgalim. He is the Kisei [ha'Kavod], and all are Ne'etzalim (emanations copied) from His great, boundless radiance. It says in Shmos (2:3) "va'Yar Mal'ach Hashem
Ramban: The Gematriya of 'Matatron' is equivalent to that of 'Shakay'. And this explains why this angel said to Ya'akov (in Vayeitzei 31:13) "Anochi ha'Keil Beis-Eil."
The Magi'a said, this is with [counting one for each of] the letters [of Elokim]. (Alternatively Mal'ach is the same Gematriya as ha'Elokim - PF)
What does the Torah mean when it writes that the names of Ya'akov and his fathers will be "called upon them"?
Ramban #1 (citing the Ibn Ezra): It means that all of Yisrael are called after Yosef. 1
Ramban #2 and Rashbam: That the children of Efrayim and Menasheh and their name will stand firm and that the name of Avraham, Yitzchak and Ya'akov will be ascribed to them forever.
Da'as Zekenim, Hadar Zekenim: They should be called Shevatim, like the other B'nei Yakov.
Yerushalmi, B'rachos,4:3: We Daven Shemoneh Esrei every day, coresponding to the eighteen times the Avos are mentioned in the Torah. 4
As we find in Tehilim (77:16) - See also Ba'al ha'Turim, and the Ramban's objection. See Ibn Ezra.
That they should be worthy of being called their children.
Because the Yichus of Tzadikim does not go back to Resha'im; neither does that of Resha'im go back to Tzadikim.
Yerushalmi (Ibid.): Including the Pasuk here, which inserts the word "Sh'mi" (representing Ya'akov, but excluding the Pasuk in Vayeitzei
What are the connotations of the word "ve'Yidgu"?
Refer to 49:22:1:3. Moshav Zekenim asks, why don't we find that Bnei Yosef lived longer, according to the opinion (Bava Metzi'a 107b) that 99 out of 100 die from Ayin ha'Ra? Since they did not die through this, they died from other maladies. Still, immunity from Ayin ha'Ra was beneficial. The entire Aleph-Beis is in verse 49:26 (in Yosef's Brachah) except for Tzadi and Tes (99).
Perhaps that is also what Targum Yonasan hints at when he adds that fish proliferate in the water.
Why does the Brachah end "b'Kerev ha'Aretz"?
Moshav Zekenim: It says "b'Kerev ha'Aretz", and not 'Al ha'Aretz' - [they will multiply greatly] even when they will go into [the depths of] forests (Yehoshua 17:15).
Peninim mi'Shulchan ha'Gra: They will multiply greatly in Eretz Yisrael. We do not see that Bnei Yosef multiplied more than the other Shevatim when they were counted at the beginning of Bamidbar and towards the end, 1 but during the seven years of conquest they multiplied greatly. Therefore, they complained to Yehoshua that the portion they received is not enough.