Questions Regarding the APP UNINSTALLED Webhook

[jeffhardy1]

Have I accidentally enabled this webhook, or are the apps already listening to it by default? While I was testing the activation of my WeBook, it only returned null (undefined) if console.log was used to print the response. I tried removing the app, and the webhook continued to function. Is it just me, or do apps automatically listen to this webhook?
The second query is: If I remove the app and already create a subscription to a webhook, do I need to recreate this subscription if the app is reinstalled, or can I keep it active already?