1)
What is the significance that they went b'Neshef (at the beginning of the night)?
1.
Malbim: This was to fulfill Elisha's prophecy "ka'Es Machar" (like this time, tomorrow). Had they waited until morning, until they would tell Beis ha'Melech [and they would send men on horses to check
1
Presumably, the men went when it first became light. They were concerned for an ambush, and one cannot see well at night. (PF)