Changing the .css, Print Document and other troubles....

I'm currently using RH 2017, Responsive Layout.  

I have used RH for 5+ years and I still have a lot of trouble creating the PDF.  We deliver both a PDF and a .html file to customers.  The PDF is only certain sections of the .html document, but it's still significant at about 600 pages.  I first generate the Word document.  This file requires that I spend probably 4-6 hours formatting it, fixing page breaks (so they are logical and clean!) , reducing/enlarging images so they look "normal" on a piece of paper, removing the dumb duplicate section titles,  adjusting table  sizes, heading rows, etc.  AND then, when I generate the PDF from the finally fixed Word doc, the numbered headers do not always display correctly as bookmarks, so I spend even more time re-creating about 60% of them.  For example, the numbering format in 1.0 Overview will display as just "Overview" in the PDF bookmarks, but 2.0 Installation, might display correctly as 2.0 Installation in the PDF bookmarks, and I can't even tell what the difference might be.  

I am so tired of this that I want to switch to a different software.  But, I can not.  I've been creating the PDF this crazy way for longer than I want to admit.  I have worked nights and weekends sometimes to meet my deadline because of all this work that has to be done.  I envy those that can create a PDF with a "one click and done" just as easily as I can generate the Responsive .html file.  I sometimes resort to shortcuts between minor releases by updating the .html  files and then MANUALLY updating a PDF file from a previous version.  

In the next few weeks I have time to break everything down and work on all these issues.  

I would like to better align my css headings. 

Right now for example I have "unit title", "section title" and then Headings 1, 2, 3, etc.  I should have used the standard Heading titles only.  So, "unit title"  should be "Heading 1" and "section title" should be Heading 2.  Is there an easy way to update the css names?

How does everyone handle all the print issues I mentioned - big images, unclean page breaks, tables that slide of the page, etc.  Or is it just me?  

p.s.

I have to say that the finished product looks really great, functions well, links work correctly, etc.  It looks as if it was  originally created in a desktop publishing software.  It just requires too much of my time and too much manual work.