1)
Why did he fight Amon?
1.
Malbim: They gave a Minchah 1 to his father (26:8), and rebelled against him.
1
I.e. the 'Minchah' was an annual tax that he imposed on them. (PF)
2)
Why does it say "Zos Heshivu Lo"?
1.
Malbim: First they returned to him the debt they owed for the years that they rebelled and did not pay the tax incumbent on them. After he decreed a fine that they pay for another two years, to punish them for their rebellion.
