You can consider to use plugins of third party such as WooCommerce & Square Integration provided by Litextension. It helps e-merchants to keep Square and WooCommerce in sync, updates between the two stores are instant. You can manage multiple sales channels easier.
You should go with your friend suggestion as it has the best idea or else ask the square developers to code your site. Hiring someone experienced coders will help to integrate, although it depends upon the price.
If you are thinking about sync data between Square and WooCommerce, Woocommerce with Square as Payment System and POS/Register can be a good information for you.
This would be ideal if merchants can directly integrate Square Payment as a credit cart processing module on their websites. But unfortunately, til now Square hasn’t opened the gate for that yet. Square integration is only available for a few chosen Partners so far.