How can I add commerce product automatically when saving a node 'product display' I want to create a default product reference with the price to zero, title to node_title, sku to author_node_title. So each time I create a display product node type I haven't to fill the product reference info. If I created one display product node type -> system will create one product and auto reference that product to display product node.

Thanks in advance!
You could use a triggered rule using Rules on the event "After saving new content", creating the product entity, saving it and editing the product reference field after as well.