I have azure staging instances running right now for QA testing.
The client has requested another instance for him and his team to test. I think that I should use production environment for this purpose.
My questions is, is the staging environment independent of the production environment?
If the application in the staging environment crash, will the production environment be safe?
Yes and Yes. Each "slot" (production and staging) in a cloud service gets deployed separately and they are independent - each slot has unique VMs running instances of the web and/or worker roles for your project. The staging slot is meant for use as a deployment slot that allows you to incrementally update your code and then with little to no user interruption, swap the VIP to move the new code into production.