Aurora Create cross-region read replica vs Add Region

I have 3 questions regarding aurora read replica:

1. When I create a cross region read replica the resulting replica cluster in the new region creates a writer instance when multi-AZ is enabled. An interesting thing is that the writer instance appears as a reader during creation and switched to a writer after creation. I would assume that the writer is disabled but why does it appear as a writer even though it is a cross-region READ replica?

2. What is the difference between read replicas created by 'Create Cross-Region Read Replica' and 'Add Region'. It seems the the underlying implementation is different: binlog based sync and storage-layer based sync. Also, they appear differently from the console - Cross-region read replica appears to be an independent cluster in another region but read replicas created by Add Region appear as a secondary of the primary cluster in the source region. Given the differences, my question is what is the difference of the two types of replicas? How do I need to guide customers when asked which one to choose?

3. Do replicas in different region automatically escalated to a primary? I guess it requires some manual work such as changing the endpoint etc.