Oh, I see. As for adding a new date to Estimated Shipping Date, the file to change would be main-product.liquid. Not sure what’s inside that file, but that’s the file to start looking for the Estimated Shipping Date code. Try using CTRL + F to look for “product_additional_information”
As for Availability, it’s in the same file, and use CTRL + F to look for “product-variant-inventory”.