What new risks should be captured in the risk register? And how often?

How do you identify risks? How do you know which risks will have a higher impact then others? What tools do you use?

What do you do as a PM when a risk is found which was not included in the Risk Register. What should you do? I want to see a step-by-step approach

You are a project manager of a project. Customer has requested a change which will increase the project risk. You need to talk to the client, what will you tell them? I want to see an approach here.

How do you Cre ate an ongoing process to identify and categorize risks?

Pls add all the references