Bitrix. Changing the logic of order payment

You need to change the logic of payment of applications on the site:
There is a site where you can make an order, the order has 5 statuses, at the moment you can pay for the order without waiting for confirmation. It is necessary:

1. Remove the possibility of paying for the order immediately after the order
2. Implement the possibility of payment after confirming the order (change of status)
3. Add email when changing order status

I'll send details to those interested.