1)
When was "Az Yada Mano'ach"?
1.
Radak #1: It goes back to when they saw the angel ascend in the flame, and not to "he did not return to appear."
2.
Radak #2: It refers to "he did not return to appear." The angel ascended in the flame, and was not seen any more. Then he knew that he is an angel. Malbim - until then, Mano'ach had a Safek - perhaps he is a man who does wonders. He was hoping that he will descend on the Mizbe'ach and return to them. Now he realized that he is an angel, and returned to his place.
2)
Why is there a Cholem in "Lehera'o"?
1.
Radak: We find like this - "Lehera'o b'Shilo" (Shmuel 1:3:21), "Hinason Tinaten" (Yirmeyah 38:3).
