Inb4 great platform and docs

Hi, I’m almost finished with my iOS app and i’m at the point where i want to integrate in-app purchases. So far so good with settings up my project in revenuecat. 

My in app purchases is a common case of ​​​​​

• consumables - coin packages
• non-consumable - lifetime access
• auto-renewal subscriptions - silver / gold - monthly / yearly

I’m using firestore and cloud functions as db and backend, and i’ve also set up the revenuecat extension for firebase. 

And let’s say on the user profile in firebase I have a field called
active_subscription = silver / gold / free / lifetime

Even though i’ve read lots of article about this, official documentation, examples etc, I still have some questions about certain flows especially Refunds

1.  I’m not sure how to handle them. If a refund is accepted by apple for a transaction, the cancellable event is triggered for the web hooks?
   1. if that is true, then in my backend hook i’ll update the profile active_subscription? then what’s the point of entitlements in my ios app? If I have realtime updates setup to listen for profile updates in firebase, they’d work in a similar manner
2. If i have to set up hooks to define custom logic in order to update my db, i don’t see why do i need the firebase extension. Is it for analytics purposes?
3. What happens if a user requests a refund for a consumable  that they used and the refund gets accepted? What do i need to do then? I can’t take back the coins if they used them already. 

I’m pretty much noob in the payment industry so please bear with me 

Thank you