Hello, Firas,
Thank you for your response.
1/ You can use XStore Studio by yourself.
Content of menu page from sushi demo was not added in the studio because tabs contain static blocks. If is it simple sections you will be able to find them and import them without our help.
2/ You need to create separate static blocks for every category.
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