Yes, 发现报告 is free to download, however it contains in-app purchases or subscription offerings.
Not enough reviews to make a reliable assessment. The app needs more user feedback.
发现报告 has several in-app purchases/subscriptions, the average in-app price is $64.99.
To get estimated revenue of 发现报告 app and other AppStore insights you can sign up to AppTail Mobile Analytics Platform.