Thanks, elfin... The reason I asked is because the site I want to install eShop to is running an old version of WP, and due to various reasons, I cannot upgrade it to the latest version. I often have trouble installing modern plugins to this site because of that. I particular have issues installing plugins requiring PHP 5. I just wanted to see if there are certain absolute requirements (such as PHP 5) for running eShop, or if the plugin's functionality could be diminished due to older versions of WP, PHP and/or MySQL.
Thanks again for the clarifications.