Hi, hope you are doing well.
You have already setup the Staging site using different theme, Now you want to add contents, products and other setting into it similar like the older website.
I have good experience in ecommerce website development, I will help you in setting up the store properly adding contents, products, adding payment and shipping method.
I am using these cms for the last 4 years WordPress, Shopify, Prestashop, Opencart, Moodle, Joomla, SquareSpace, Wix. I am also good at custom coding Php, Html/CSS.
Please invite me on chat so we can discuss it further.
Thanks