Hello,
1. You need to install the multilingual plugin, we suggest to install WPML https://wpml.org/ it is 100% compatible with the theme. Then you will add a shorcode to the header builder in the text block.
2. Please enable “Quantity input on product”, this option is provided for some of the on hover designs, for example, the Standard button
3. I will check for a better suggestion with my dev team and we shall get back to your
Best Regards