The Analytics tracking code may be directly added directly to the HTML of each page on your site, or indirectly using a tag management system such as Google Tag Manager.
Please go to Admin > Theme Options > Settings > Custom Code
For all customization purposes, this framework allows you to load multiple CSS/JS files you customized without altering the template core files.
You can include css/js files by adding file path per line. You can use Full URL of the CSS/JS file, or path of the CSS/JS file relative to the Joomla root directory.