Thank you for the details.
Fatal error: Cannot redeclare class Cornerstone_Plugin_Base in /home/********/public_html/wp-content/plugins/cornerstone/includes/utility/plugin-base.php on
This error will only appear if you activate Cornerstone while Pro theme is installed and Active. Please be informed that Cornerstone is already integrated in Pro theme. You do not need to activate Cornerstone anymore.
And yes, there is no activation for the Grid plugin because that is a bundled plugin. All plugin updates will be provided by Themeco. To know more about thr grid plugin and how it is integrated in the theme, please check this out:
Please let us know how it goes.