1)
Did Hashem Himself tell Shlomo?
1.
Radak: No, He told him via a Navi - Achiyah ha'Shiloni.
2)
What is the meaning of "Asher Haysah Zos Imach"?
1.
Rashi: You knew that you transgress my Mitzvah.
2.
Malbim: Even though you yourself did not serve idolatry, it was in your Reshus and in Yerushalayim.
3)
What Bris did Shlomo transgress?
1.
Malbim: He was obligated to eradicate idolatry.
4)
Why was kingship given to his slave?
1.
Malbim: This was Midah k'Neged Midah. They worshipped Tzva ha'Shamayim (Heavenly bodies), which are Hashem's servants, and 'removed' His kingship, so Shlomo's kingship will be removed and given to his slave.