Stripe webhooks with laravel

Hi everybody, I have a laravel app where I want to enable Stripe payments, particuraly the asynchronous flow using webhooks! I haven't used webhooks yet so I'm pretty confused and have a few questions:

First I create a paymentIntent in the server and send the PI secret to client.

public function createPaymentIntent(Request $request)
    {

            $intent = PaymentIntent::create([
                'setup_future_usage' => 'off_session',
                'amount' => 1099,
                'currency' => 'usd',
            ]);

            return response()->json([
                'intent_secret' => $intent->client_secret,
            ], 200); 

        
    }

Now in client I execute confirmCardPayment, this returns a Promise

this.stripe.confirmCardPayment(
        this.intent_secret,
        {
            payment_method: {card: this.cardNumberElement}
        }
        )
        .then(function(result)
        {
            if (result.error) 
            {
            // Display error.message in your UI.
            }
            else
            {
            // The payment has succeeded
            // Display a success message
            }
        });

Now this is when it gets confusing, apparently I have to setup webhooks to listen for when auth/payment is completed, I checked the docs and I salvaged their PHP example into my laravel code but I have so many questions:

public function stripeWebhook(Request $request)
    {

        // You can find your endpoint's secret in your webhook settings
        $endpoint_secret = config('services.stripe.webhooksecret');

        $payload = @file_get_contents('php://input');
        $sig_header = $_SERVER['HTTP_STRIPE_SIGNATURE'];
        $event = null;

        try
        {
            $event = \Stripe\Webhook::constructEvent($payload, $sig_header, $endpoint_secret);
        } 
        catch(\UnexpectedValueException $e)
        {
                // Invalid payload
                return response()->json([
                    'message' => 'Invalid payload',
                ], 200);
        }
        catch(\Stripe\Exception\SignatureVerificationException $e)
        {
            // Invalid signature
            return response()->json([
                'message' => 'Invalid signature',
            ], 200);
        }

        if ($event->type == "payment_intent.succeeded")
        {
            //As I understand here is where I should do things like send order info by mail and deplete stock accordingly

            $intent = $event->data->object;

            //$this->completeOrderInDatabase()
            //$this->sendMail();

            return response()->json([
                'intentId' => $intent->id,
                'message' => 'Payment succeded'
            ], 200); 
        } 
        elseif ($event->type == "payment_intent.payment_failed")
        {
            //Payment failed to be completed
            
            $intent = $event->data->object;
            $error_message = $intent->last_payment_error ? $intent->last_payment_error->message : "";

            return response()->json([
                'intentId' => $intent->id,
                'message' => 'Payment failed: '.$error_message
            ], 400); 
        }

        
    }

So first, am I supposed to create a POST route called domain.com/webhook from where I will call my webhookController method?

Second, what is payload and signature? these seem like required params but I don't know what exactly they are...

Where am I supossed to attach the payment method to the customer? In the docs I'm supossed to get the payment method from PaymentIntent object but is that in client or server.

https://stripe.com/docs/payments/payment-intents/migration#saving-cards-checkout

From the docs:

$payment_method = \Stripe\PaymentMethod::retrieve('{{PAYMENT_METHOD_ID}}');
$payment_method->attach(['customer' => '{{CUSTOMER_ID}}']);