ox-pandoc VS olivetti

You can use the ox-pandoc library to export from Org Mode in Emacs to 65 different formats (at time of writing) including all the ones you mention.

For some formats that pandoc does not output, there are also specialised ox-format libraries.

There are even several exporters to Github-flavoured markdown. I personally find both ox-pandoc and ox-gfm very useful for that purpose.

https://github.com/kawabata/ox-pandoc

Orgmode's page about tools about import & export actually includes both to an entry about export to pandoc (ox-pandoc) as well as import from pandoc (org-pandoc-import).

You need to install some package for that; have a look at https://github.com/kawabata/ox-pandoc for example.

The ox-pandoc package is really useful (you need to have pandoc itself installed) and can export to epub using just the export function of org-mode itself. (That, in turn, is described thoroughly in the org manual.)

It's always nice to see someone from the humanities interested in Emacs. I suspect that you'll find the best experience by using Org mode + Pandoc. This will let you write in a rather nice plaintext environment, and then export that to a .docx file. I don't think the styling will be great (could well be wrong though), but it should work fairly well :) Importing (from .docx to .org) is likely to be less smooth, but still decent.

Can also export directly to word through pandoc as well; there's a package ox-pandoc, which lets you do just that, and you can even include a reference document in case you need to have custom styles added to it.

If you want an easy, bare bones PDF export that is not LaTeX and doesn't require a bunch of fiddling to make it not look an LaTeX article, using ox-pandoc with the "mspdf" export (using pdfroff as the pdf generator) is decent. It doesn't support embedded images, but is otherwise pretty robust.

I also use writeroom because I prefer its simplicity, but worth mentioning that olivetti is the more popular writing mode.

There are nice looking distraction-free setups with https://github.com/joostkremers/writeroom-mode or https://github.com/rnkn/olivetti or https://github.com/joaotavora/darkroom or https://github.com/rougier/nano-emacs

For batteries-included packages that give you dedicated prose-writing modes, see also olivetti and writeroom-mode.

You could use olivetti-mode or Writeroom mode.

Another option is the Olivetti package. https://github.com/rnkn/olivetti

Don't have a specific tutorial except to suggest setting org-mode to use olivetti and a nice variable pitch font for writing prose. You might also like the poet theme.

If you want to try out some third-party packages in the beginning, I think the most "bang-for-your-buck" you'll get is with Avy. Also, expand-region. And specifically for writing: olivetti-mode, flyspell, dictionary, and Nicolas Rougier's Nano and Elegant Emacs setups.