Hello,
1) Contact WooCommerce plugin about this. If you are using Elementor for products, maybe support of this plugin will be able to give you some suggestions.
If the description is the same for all products, you can create a static block with the desired content, and add it in the description area via shortcode.
2) Create a translation for the theme and Core plugin – https://www.8theme.com/documentation/xstore/theme-translation/base-theme-translation/
Synchronize translation fo the WooCommerce plugin – https://www.8theme.com/documentation/xstore/theme-translation/translation-files-update/ , then find and translate the text.
3) This is independent of the theme.
4) There is 1 custom tab – https://prnt.sc/xjtl7c
If you want to add more tabs, contact the support of the WooCommerce plugin to get some advice.
Regards















