Hello, Kostas,
Thank you for choosing XStore as your WooCommerce WordPress theme.
1/ You have not provided URL of product, so we’ve checked a random product and we do not see mentioned problems – https://prnt.sc/0sq8MEuEPa51 https://prnt.sc/0gtVHKOphR1k
2/ “….which is the logical way to display” – we recommend that you contact the support team of the WooCommerce plugin – https://wordpress.org/support/plugin/woocommerce/ , because there are no additional settings for this from our theme side, unfortunately.
3/ “Hide out of stock items from the catalog” needs to be enabled in WooCommerce > Settings > Products > Inventory.
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.
Kind Regards,
8theme team