To make .yaml files more easily, there is this tool that Hendrik made: nathanlesage/pandoc-profile-generator
As for sharing asset files, one way would be to just post them here on the forum. For example, the beginning of my "markdown to XeLaTex-PDF" yaml looks like this:
reader: markdown
writer: pdf
self-contained: true
variables:
# Sets the size of the document's pages.
papersize: a4 # Possible values: a0-a6, b0-b6, c0-c6,b0j, letter, executive, legal
mainfont: "Garamond"
sansfont: "Arial"
linestretch: 1.3 # 1.3 means 130% linespacing
margin-left: 2cm
margin-right: 2cm
margin-top: 2cm
margin-bottom: 2cm
And that's enough to get a pdf that looks a bit nicer to me (and not quite as obviously "stock latex")