Hello,

You are Most Welcome.

1) I saw the screenshot you attached. I have visited your website and the category item dresses are working absolutely fine on my end. Please clear cache and check back.

Screenshot for Clarification: https://ibb.co/4Mk62Lb

2) You need to create a page and set it as the custom 404 page from Theme Settings >> General.

Screenshot for Clarification: https://ibb.co/GRdqxr3

Best Regards.