1)
What did they call?
1.
Rashi: During the war, they announced a metaphor of shame.
2.
Radak: In Egypt, they called to Pharaoh, who was a boisterous king over multitudes.
3.
Radak citing Targum Yonasan: They summonsed Pharaoh to there.
4.
Malbim: Initially they announced that Pharaoh is coming noisily with multitudes.
2)
Why is Pharaoh called "Sha'on"?
1.
Rashi: He raised his voice to boast about his soldiers.
2.
Radak: The word "Melech" applies also Sha'on; he was a boisterous king over multitudes.
3)
What is the meaning of "He'evir ha'Mo'ed"?
1.
Rashi: He fixed a time to go out to fight, and he did not go out (Radak - due to fear of Melech Bavel); the designated day passed.