Page Categories Access Issue

I have purchased the pro version of the software and want to lock down access to certain pages based on category. I have created a category “Core” and put my core pages I don’t want editing by anyone other than admin. If I edit the page category access and tick under “Backend” “List – Hide Core” to prevent a user seeing the category when editing a page, it then allows them to edit any page within the category (I have ticked the other boxes to restrict editing). If I untick “Backend” “List – Hide Core” then the category is available for them under edit, but they can’t then edit pages set to “Core” (which is correct as edit has been restricted).

Also is there a way to set default access unless specified for post categories. I want to lock some people to only be able to post under certain categories, which I have setup, but if a new category is added then this is open to all users to post under by default?