Until now, it says Rechav'am. Why does it say here "ha'Melech"?
Malbim: He considered himself to be one who rules by himself, and need not consult with the nation and fulfill their requests.
Why does it say "bi'Hyoso Chai"?
Radak: Even when Shlomo was dead, they showed themselves as if they were standing in front of Shlomo alive; they gave a proper counsel to his son Rechav'am.
Why did he say "Eich Atem No'atzim", and not Mah Atem No'atzim?
Malbim: He did not ask whether or not to fulfill their request. He already decided not to fulfill it, and rule an unlimited kingship. He asked counsel only about how to dispel them - with soft words, with guile, or with harsh, frightening words.
What is the meaning of "Eich Atem No'atzim"?
'Rashi' (Divrei ha'Yamim II, 10:6): This is like Yo'atzim, just like from Yod'im we say Nod'im, just Yo'atzim is future and No'atzim is how you already counseled.
Radak: How do you counsel among yourselves, to give to me counsel?