third-party-applications

Yes, of course you can make any type of web app. Use Page Templates for different pages, Custom Post Types for different data handlers, Taxonomies for categorizing those data, and Plugins for advanced functionality. WP Codex is best way to dive into WordPress.

You have to include libraries CSS and JavaScript files to your theme (preferably in your Child Theme to keep customizations separate from the parent theme’s files). In order to do that you enqueue scripts and styles in the themes functions.php file. From the Including CSS & JavaScript Theme Handbook: Enqueue the script or style using … Read more