Sharon, there is no way to forcibly limit copy/paste actions, since the only thing that is transmitted to WikiTree is the content of the edit box - WikiTree programming has no way to know whether that content was typed in directly or pasted in … and, by the way, many people work offline or in a text editor or word processor for their convenience and then paste what they have written into the edit box and there is certainly nothing wrong with that.
WikiTree policy does include not plagiarizing and not violating copyrights by copying the entire content of an article found elsewhere and pasting it into a biography but the only way to "police" it is for members who happen to find an instance of it to write to the member who put it there and tell them that it has to be removed, then give the member some time to do so before going back and doing it themselves.
WikiTree policy also states a preference for inline citations, but allows the option of simply adding the citations at the end of the Sources section to accommodate members who do not know how to code the inline references.
Inline references, however, do not automatically make the citations any better than if they're just added at the end. It is the citation itself that needs to be complete and accurate and provide a link if the information is available online.
I am in full agreement with your wishes for having no copyright violations, plagiarism, or incomplete source citations. I applaud your initiative and want to assure you that all the help you need to become an expert WikiTreer is right at your fingertips - and I mean that literally! You can ask questions here about pretty much anything and someone will give you answers and/or explanations that will be fast and good.