What are the connotations of "Vayishman Yeshurun Vayiv'at"?
Seforno: It means that Yisrael 1 behaved like animals which lash out at the person who comes to feed them. 2: Targum Onkelos and Targum Yonasan: It means that Yisrael became wealthy and lashed out' (and despised Hashem - Targum Yonasan)..
Refer to 32:15:2:1. Even the most cultured among them, as inherent in the word "Yeshurun" (Oznayim la'Torah).
Sha'arei Teshuvah (1:30): Because as long as a person follows his physical desires, he is drawn after the physical, and distances himself from the intellectual Nefesh, and his Yeitzer ha'Ra overpowers him. See Oznayim la'Torah in Pasuk 14 DH "Vayishman Yeshurun".
B'rachois, 32a: Hence the mantra 'A full stomach leads to terrible sins'.
Why does the Torah refer to Yisrael here as "Yeshurun"?
Seforno: Because it is talking even about people who are studious - the wise among them. 1
Seforno: As in Bamidbar, 24:17 "Ashurenu veLo Atah".
What is the difference between "Shamanta", "Avisa
Rashi: 'You became fat, thick and obese, with a triple layer of fat.
Seforno: "Shamanta" - 'You (Refer to 32:15:2:1) became dense (mentally)', because you turned to the material pleasures of this world; "Avisa" - 'You were unable to discern the finer points of truth' 1 - and "Kasisa" - 'Your eyes were smeared' (preventing you) from seeing the truth and your hearts from comprehending. 2
Targum Onkelos and Targum Yonasan: 'You were successful, became strong and acquired property'.
What is the meaning of "Vayenabel Tzur Yeshu'aso"?
Seforno: It means that they disgraced the Rock of their salvation by going from bad to worse.
Rashbam: It means that they acted foolishly against the Rock of their salvation.
Targum Onkelos and Targum Yonasan: It means that they angered the Mighty One who redeemed them.'
Oznayim la'Torah. Refer to answer #2. Initially, "Vayitosh Eloka Asahu" - they lashed out at Hashem, though in their hearts they still believed that Hashem had created them; Then "Vayenabel Tzur Yeshu'aso"; they sacrificed to Hashem in conjunction with Avodah Zarah 3 - What can be more disgusting than that?! And finally, "Yizb'chu la'Sheidim Lo Elo'ah" 4 - They denied Hashem altogether.