When did Michah prophesize?
Rashi (Hoshe'a 1:2, from Pesachim 87b): He was the last of four Nevi'im [whose Nevu'os are Seforim in Tanach] who prophesized at the same time ? Ho
She'a, Yeshayah, Amos and Michah. Michah prophesized "bi'Ymei Yosam Achaz Chizkiyah"; the other prophesized also beforehand in the days of Uziyah. Radak ? it does not mention Malchei Yisrael at the time. Since it said "Asher Chazah Al Shomron", it is as if it mentioned Malchei Yisrael.
What is "ha'Morashti"?
Rashi citing Targum Yonasan: He is from the city Morishah. Radak ? it is in Yehudah.
Do we find Michah outside this Sefer?
Radak: Yes - "Michah ha'Morashti Hayah Navi? va'Yomer? Tziyon Sadeh Secharesh" (Yirmeyah 26:18). (Refer to 1:2:1:1*.)
