1- How can I set a configuration Item and a service automatically when selecting a caller? I already related each caller to his CI and service, but I want them to be selected automatically in a service call once I choose the caller.
I'm not really sure why you would want to auto populate the CI of a Service Call based on the caller. That will only work if the caller only uses one CI. You can create a UI rule that will take the service from the CI and populate it into the Service Call when you enter the CI.