Hello,

-You need to install the Visual Composer plugins first. Find it in the included plugins list. Go to the main theme file you downloaded from Envato. Open ‘extra-plugins’ folder and install the js_composer.zip file.

-Revision of pages is a basic wordpress feature. To make it show up, go to Screen options (top-right corner of every wp page); Check the “Revisions” checkbox;
If you do not have this box, go to file wp-config.php and add these two lines:

define('AUTOSAVE_INTERVAL', 300); 
define( 'WP_POST_REVISIONS', true );

Now the revisions should be showing on the post-edit page and the Revisions option should be back in the Screen Options menu.

-Please make sure you do have selected a page for the checkout in plugin’s options:
WooCommerce > Settings > Checkout > Checkout pages.
Let us know.

Best regards!