1)
Why does it say "v'Ede'ah"?
1.
Malbim (9): Nechemyah wanted to return also Terumos and Ma'aseros to the chamber. Via this, he found out that the nation was not giving them.
2)
Why does it say "Lo Nitenah" (singular)?
1.
Malbim: It refers to the Mitzvah of giving.
3)
What is the connection between not giving Matanos Leviyim and the Leviyim fleeing?
1.
Rashi: Because the Matanos were not given there (in the chamber), Leviyim went to and fro to request their Matanos, and did not engage in their Avodah so much.
2.
Malbim: Because they did not receive their Ma'aser, they abandoned it, and went to engage in working their fields.
