Why does the Torah interrupt here in the middle of the episode of Yosef and his brothers?
Rashbam: Because it provides us with an additional reason as to why they hated him. 1
As is evident from the next Pasuk.
What is the meaning of "Ben Zekunim hu Lo"?
Rashi #1: It means that he was born to him in his old age. 1
Rashi #2 and Targum Yonasan: "Zekunim" is the acronym of 'Ziv Ikunim' - because Yosef was the spitting image of Ya'akov.
Rashi #3 (citing Targum Onkelos): He was his wise son 2 - because he taught him everything that he learned in the Yeshivah of Shem and Eiver.
Ramban and Malbim: It was customary for old men to pick one of their younger children to serve them and to lean on - and he was called a 'ben Zekunim'.
Rashbam: Ya'akov favored him because he was the last of the eleven sons to be born - Binyamin was born much later.
Hadar Zekenim: Even though Binyamin was born later, Ya'akov did not love him as much, for Rachel died through his birth. Alternatively, Binyamin was too young (nine), and one does not love a young son so much. Also Ya'akov saw with Ru'ach ha'Kodesh that when Ya'akov is old, Yosef will be king.
As Chazal have said "Ein Zakein Ela Mi she'Kanah Chochmah"
What exactly is a "Kesones Pasim"?
Rashi #1: It is 'a cloak of fine wool. 1 '
Rashi #2 (in Shabbos 10b), Da'as Zekenim: It is 'the part of a cloak that covers the hands' 2 and that is made of fine wool.
Rashi #3: Pasim is the acronym of 'Potifar, Sochraim, Yishme'elim, Midyanim', who bought him (though not in that order), due to the [envy that came due to the] robe. 3
Ramban (Shemos 28:2): It is 'an embroidered, striped cloak'.
Rashbam: 'It is a long coat'.
Targum Yonasan: It is 'a colored cloak'.
Oznayim la'Torah: It hints at Keri'as Yam-Suf. 4
Ha'amek Davar: It reached until Pas Yado (his palm).
Why did Ya'akov make the special robe for Yosef?
Rashi, Ramban, Targum Onkelos and Targum Yonasan: Refer to 37:3:2:1-4.
Oznayim la'Torah (citing Midrash Rabah): He did it as a sign that the Yam-Suf would split on the merit of Yosef. 2
Malbim: The other brothers were always in the field with the flock; they dressed like shepherds. Yosef served Ya'akov in the house, and needed honorable clothes for his father's honor, like Eisav had [special] clothes to serve his father.
Why did Ya'akov not make the special robe for Binyamin, who was born when Ya'akov was even older?
Rosh: Precisely because he was too small to keep it clean.
How could Ya'akov not take into account the brothers' reaction to his display of favoritism?
The Gemara in Shabbos 10b does indeed comment that Ya'akov erred in this point - A father should never display favoritism to one son over another. And it concludes that, for two Sela'im of fine wool - the Kesones Pasim that Ya'akov made for Yosef over and above his brothers - they became jealous of him and, after one thing led to another, our fathers ended up going down to Egypt. 1
Rosh, Moshav Zekenim: Even though exile was already decreed at the Bris Bein ha'Besarim, if not for the special robe, it would have entailed merely going from one land to another
The previous verses said "Ya'akov". Why does this verse say "Yisrael"? The next verse says that his brothers saw that he loved him "mi'Kol Echav." Why does this verse say "mi'Kol Banav"?
Ha'amek Davar: His love for Yosef was not due to physical matters and service. Rather, there were spiritual reasons to love him. Ya'akov loved him "mi'Kol Banav", for his nature resembled Ya'akov more than the others. 1
Presumably, his brothers did not realize this, therefore it says that they saw (assumed) that he loves him "mi'Kol Echav." (PF)