Why does it mention Yakov and Yisrael?
Radak: The matter is repeated in different words. Both refer to the 10 tribes ? they were the majority, and it was due to Malchus Efrayim.
Malbim: Yakov refers to the 10 tribes; Yisrael refers to Yehudah and Binyamin.
What is the meaning of "Mi Fesha Yakov"?
Radak: Who caused the sin of Yakov, i.e. the calves? I am forced to explain so, for 'Mi' always refers to someone with intellect, e.g. "Mi ha'Ish" (Devarim 20:8). It never says Mi ha'Shor or Mi ha'Chamor 1 .
Malbim: All this will be due to the sin of Yakov, i.e. the 10 tribes. They sinned against Hashem in the way of rebellion. Yehudah and Binyamin did not rebel. They sinned due to desire or b'Shogeg, e.g. offering on Bamos. Even though this was forbidden, most of them were to Shamayim.
Even though it says "Mi Atah Har ha'Gadol" (Zecharyah 4:7), Radak explained there that it refers to people [who tried to stop building the Mikdash]. (PF)
Why does it say "ha'Lo Shomron"?
Radak, Malbim: It refers to Melech Shomron. Shomron was the capitol of Malchei Yisrael from Amri and onwards. Had they stopped Avodas ha'Agalim, Yisrael would not have served them. All the more so, they strengthened their Avodah, and the nation follows the king.
What is the meaning of "u'Mi Bamos Yehudah ha'Lo Yerushalayim"?
Radak: Who caused them to make Bamos in Arei Yehudah? The kings of Yerushalayim. It was the capitol of Malchus [Yehudah]. Malbim ? they caused the Bamos ? they did not eradicate them until the days of Chizkiyah.