Why are extra </> and <//> tags added to the template when I switch from the code view to the WYSIWYG view several times?
This is a known issue with the Internet Explorer browser and how it manages the data entered into the form. There is no way to fix this issue, as it is specifically how the Browser works. To resolve this issue, you can either use Firefox with the WYSIWYG editor, or do not use WYSIWYG.
This issue does not exist with the CKEditor added in v8.2.