How to interpret the reward after defeating an monster
You are correct.

The hero receives an amount of gold equal to the monster’s gold icon (found on the monster strength track) OR an amount of willpower equal to the monster’s willpower icon OR a combination of the two. Example: After defeating a gor, the hero may take 2 gold, 2 willpower, or 1 gold and 1 willpower.

[Edit] and of course, if you win 4, you can chose any combination of gold and willpower.