What does "Yamim Rabim" comprise? What is the significance of that time period?
Rashi: It comprises the 22 year period that Yosef was separated from him, 1 corresponding to the 22 years that he stayed away from his parents - 20 years with Lavan 2 plus two years on the journey home (eighteen months in Sukos and six, in Beis-El).
From 17 till thirty (when he stood before Pharaoh, plus the seven years of plenty and the two years of famine, after which Yakov went down to Egypt.
That is why Yakov added the word "Li" when he said to Lavan "Zeh Li Esrim Shanah b'Veisecha" - The 20 years that I spent with you will rebound on me (in that he was destined to lose Yosef because of them).
Why does the Torah state that Yakov rent "Simlosav", whereas in Pasuk 29, in connection with Reuven, it uses the word "Begadav"?
Oznayim la'Torah: Because, 'Simlah' is by definition, an important garment, one that Yakov, the head of the family, would have worn, but not Reuven. Alternatively, Reuven wore sackcloth 1 because he was doing Teshuvah.
Ha'Emek Davar: Yakov tore Simlosav, i.e. all his important garments, even what he was not wearing at the time. We find that R. Yochanan tore 13 garments due to R. Chanina's death (Mo'ed Katan 24a)! Reuven was in the field; he tore only the garments he was wearing then.
What exactly did Yakov place on his loins, and why?
Seforno: A sort of woven belt made of hemp, the material from which, due to its thickness, one manufactures sacks. Malbim - he tore his clothes due to mourning, and wore sackcloth for Teshuvah. 1
Malbim: If one sent a Shali'ach in a dangerous place, and he was killed, he must repent (Maharil. Also others cite this in the name of Maharil, based on Teshuvas Chasam Sofer OC 177 or 184. The correct text should say Mahariyo (Mahari Veil, 125). - PF)