Yes, AR 繪圖:素描與繪畫 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.
AR 繪圖:素描與繪畫 is free.
To get estimated revenue of AR 繪圖:素描與繪畫 app and other AppStore insights you can sign up to AppTail Mobile Analytics Platform.