1)
Here it says "Es Kol Divrei ha'Sefer." In Divrei ha'Yamim II, 34:24 it says "Es Kol ha'Alos ka'Kesuvos Al ha'Sefer"!
1.
Malbim (Divrei ha'Yamim II, 34:24): There it explains that they read only the Tochachah (curses) in Sefer Devarim. The Sefer was rolled to there (Yuma 52b).
2)
Did the king himself read the Sefer?
1.
Radak: He commanded to read it. It is as if he read it. The same applies to "va'Yiven Shlomo Es ha'Bayis" (Melachim I, 6:9). In Divrei ha'Yamim II, 34:24 it says "Asher Kara Lifnei Melech Yehudah."
2.
Radak citing Sukah 38b: This teaches that one who hears is like one who answers (reads himself).
