Most Welcome,

2) I have seen you screenshot. You do not have to select a category from the categories or tag option. I described you to create an html block and then use the short code inside the specific category description from the Products >> Categories: https://jmp.sh/2EYgtpx

3) As you said that most of your products do not have variations. You can share the URL of specific product in which that tab exist so I can remove the “Additional Information” tab for you. Also share the login credentials of your site.

4) I’m glad that you resolved the issue by yourself. You are the best.

5) You can select a category from the product edit page as in the screenshot: https://jmp.sh/yqABzGC

For example, if you have three products and all of them are of the same category then in the related products section of all these three products the other remaining 2 products will be shown.

6) We do not need to write CSS code to achieve this. You can simply display the title again by edit those pages title section.

Remember that if you switched off the title of shop page then the categories and subcategories also did not shown the title.

Best Regards.