Yes, 巣ごもり青空文庫 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.
巣ごもり青空文庫 is free.
To get estimated revenue of 巣ごもり青空文庫 app and other AppStore insights you can sign up to AppTail Mobile Analytics Platform.