1)
Where does man go to work?
1.
Bava Metzi'a 83b: The Tzadikim go to receive their reward.
2.
Radak: He goes to the field.
2)
Why does it say "Adei Erev"?
1.
Bava Metzi'a 83b #1: (The standard workday is until dark, i.e. when stars are visible.) A worker goes home on his own time (he leaves at dark).
2.
Bava Metzi'a 83b #2: This refers to one who completed his work (was a Tzadik) until the day of death.
3.
Radak: At night man returns to the city, and the Chayos roam to seek their prey. Hashem arranged everything with Chachmah!
4.
Malbim: Everyone has his boundary and time. Man rests at night, and darkness is good for him; Chayos rest during the day, [and hide] due to man.