Yes, 减肥 - 每日追踪 is completely free and it doesn't have any in-app purchases or subscriptions.
Not enough reviews to make a reliable assessment. The app needs more user feedback.
减肥 - 每日追踪 is free.
To get estimated revenue of 减肥 - 每日追踪 app and other AppStore insights you can sign up to AppTail Mobile Analytics Platform.