Some additional general tips:
A better way of formatting is using styles instead of manual manipulations like adding lines for a page layout in Word. A TOC should be generated within Word by using headline styles. calibre will recognize headline styles as TOC. Save a document in format DOCX and not RTF. This format is much better supported from calibre as RTF and you can open it directly with the editor.
A well formatted Word document will be a much better source file. You can open the DOCX file directly in calibre editor with repeatable results all the time (or as conversion) and you then only need the editor as fine tuning tool (and/or for checking how it looks as EPUB).
Take a close look to the calibre manual. There you will find a comprehensive DOCX example and how to use Word styles in combination with calibre editor. This will answer most of your questions how to make a much better source document for building a EPUB.
https://manual.calibre-ebook.com/con...-specific-tips (Convert Microsoft Word documents)
https://calibre-ebook.com/downloads/demos/demo.docx