Hello, Kestutis
1/ Please re-check your settings – https://xstore.helpscoutdocs.com/article/87-facebook-login
If you find a plugin that works fine and does not have compatibility issues with our theme, you can use that plugin.
2/There is no such possibility, by default, unfortunately.
We inherit registration functionality from WooCommerce plugin, if you want to customize it, contact the support of WooCommerce to get advice.
Sorry, but additional customization is outside the scope of our basic support.
If you have any additional questions or concerns, please do not hesitate to reach out to us. Our support team is always available to assist you.
Best Regards,
8Themes Team