Holding WANA through staking mechanisms allows you to earn even more of both coins and some other game items.
As I currently see it, only if you play the game. And the interest rate, which is up to 25% APR, is depending on your rank and on the staking period.
Excellent question. No, it is not necessary to play the game to stake WANA. The ranks are defined by the amount of WANA to stake. In the promotional image that they published, that is not very clear, I'm sorry. Added this screenshot from the staking site for clarity.
Then this is an attractive investment option. Thank you for the clarification.