1)
What is "Matan Kohen ha'Ba'al"?
1.
Radak: The name of Kohen ha'Ba'al was Matan.
2)
What are "Pekudos"?
1.
Rashi: They are people appointed to guard in the proper places. Asalyah had annulled them.
2.
Radak citing Targum Yonasan: It is the Mishmaros of Kehunah. Because they had been serving Ba'al, nothing in Beis Hashem was in its proper order. Also Divrei ha'Yamim II, 23:18 says that Yehoyada [re]established the Mishmaros of Kehunah and Leviyah that David had divided to offer Olos