[Quoth]

(1), (2*), (3), (4)
All of these can be solved by doing paragraph styles directly in Word or LO Writer.

Also
Only single spaces
No tabs
No empty lines
Use a heading level in header paragraph styles
5) You can't have headers and footers on ebooks, except when an ereader (device or app) adds them.

2*) Fonts: This won't work on some phone apps, won't work ever on older Kindles and only work on later Kindles if the user manually selects Publisher in Theme. Various authors have done this and the reason you almost never see it on paper is that it's tiring to read. Good use of direct speech tags, "action" tags and context is what works. See also Terry Pratchett's "Witches Abroad" where you'd know which Witch is speaking even without tags.


I've been involved in paper document generation since 1981 and multimedia since 1992. I realised back in 2012 that with books you need to make and proof the ebook first. Buy a cheapest eink Kindle and also a 7″ or 8″ Kobo eink model. Convert the docx version styled for ebook (small page size, no headers or footers, no line height settings) to epub2 and proof on the Kobo. Use Kobo Utilities to read back annotations.
Amazon delivers mobi, azw3 or kfx to customers from an epub2 you upload via KDP. Smashwords & Google will use the same file. Smashwords will redistribute to Apple, Kobo, Barnes&Noble and others.
You can make mobi and azw from the epub2 on Calibre for local tests on the 6″ Kindle eink (A 2022 Basic will do). You can also make a dual mobi, purely for Kindle customers of Smashwords (as they can't automatically send the correct kind to a Kindle).
Look at Lithium and Pocketbook apps (free versions) on Android. Many free Android apps don't display correctly. I forget which app should be used on iOS/iPhone/iPad. The Apple Books id for ebooks bought from Apple. The Amazon Kindle app on iOS is like an old Kindle in display rendering, different from Amazon on Android (or Fire).
The Apple, Amazon, Kobo & Google ereader apps are best only for those stores.

Don't use direct formatting (alignment, indents, size, font), use styles. The two contentious exceptions are italics and bold of part of a paragraph, a whole Paragraph in Bold or Italic needs styled in the Paragraph style.
Only set spacing to sides or above /below a paragraph using Margin in Styles (Padding is mostly for page breaks).
Set an Insert page (no style) in style of any heading needing a new page. Don't use any page styles or manually inserted page breaks in an ebook.

When the ebook is perfect (content and formatting) you make a copy and set page styles for front matter, chapter first page, left page, right page and rear matter. Then set headers & footers as desired on the different page styles. Ensure large enough inner margin.
Paper may want different fonts to an ebook. The paper DPI is fixed. The ebook display in ereaders or apps can vary from about 82 dpi to 300 dpi. Screen size is 4.3″ (smallest Android phone), to 4.7″ (smallest eink) to 10″ or larger. The eink are mostly 4:3 shape and Android mostly 16:9 shape. So Paper version has absolute sized images but the larger ebook image CSS will need edited in Calibre to be either width: 90% height: auto or vice versa. They are centred in the wordprocessor by "Anchor as Character" and on their own line in paragraph that has a centre style of text.
Only use a newline instead of a new paragraph for multiline headings (headings too long for a small page or screen) which might be Shift Enter.

Directly export the PDF for paper print. Never upload them a docx.