Use WPML plugin to make your site multilingual, Moreover see the documentation to understand how this work: https://wpml.org/documentation/

Third party plugin can’t be recommended as official compatibility assurance is not provided with the theme so advised to use only recommended plugins along with the theme.

A child theme is how WordPress help you add code or customization to a “parent” theme without truly modifying parent theme. We suggest everyone use a child theme when setting up their site to avoid any potential loss while theme version update. Please follow the link given below, in this way you can create child theme & modify it as per your requirement. https://codex.wordpress.org/Child_Themes

  1. Make sure you have added valid email address in contact form Element.
  2. Check by deactivating third party plugins that might conflict with theme.
  3. If still issue persists ask your hosting provider to enable wp_mail() function for your site to fix your issue.

There are several ways to add custom css to your site:

  1. Add custom css in Customizer > Custom CSS
  2. Add custom css in style.css
  3. Create a child theme

ItCode Theme includes several great plugins which greatly enrich the functionality of the theme. While these plugins could be placed inside the theme it’s much better to keep them as separate plugins. However, this means that plugins will have to be updated separately from the theme update.

Note: Always check Change Log while theme update, don’t forget to update plugins as well. If any!

Go to the Customizer > Site Ident you can upload logo as per your desire for your site.

  1. Reduce the size of images.
  2. Use WordPress cache plugin i-e WP super cache.
  3. Choose best hosting service for your website.
  4. Remove Unused Plugins