Why do I have 3 different “Description” boxes for the hydraulic calculation category?
Yoast SEO has three description fields each appended with what the description is for; Twitter Description, Facebook Description, Meta Description.
Additionally, WordPress core has a description field that may be used by your theme; usually displayed on the category archive page above the list of posts assigned to the category.
If you have other description fields, they could be part of your theme or another plugin. Please provide a screenshot of where you see these description. You can use any image sharing service like https://pasteboard.co/, https://snag.gy/, https://imgur.com/, or even upload the screenshot to your own website.
Site map settings: What exactly is the default setting?
By default, everything except attachment pages are set to ‘Yes’ or index. You can change these global settings under Admin > SEO > Search Appearance for all pieces of the same content types. You can, also, change this on a case by case basis when editing a piece of content under the ‘Advanced’ section.
then it gives me the options of include or exclude.. I would want to of course include everything.
Yoast SEO doesn’t have any include/exclude settings so I’m not sure what field you are seeing. Please provide a screenshot.
How does the relative priority works? What do those numbers mean?
Yoast SEO does not have a relative priority setting either. Perhaps this is something from another plugin or theme? Please provide a screenshot.