Hi there! I know I’m not Nelson, but I recently tackled this on my own site. I created another page where I keep a Rich Text element to adjust styles. Give the element the same class name as your CMS Rich Text element and then style away! All of your styles will be mirrored for the CMS version.
As for replacing bullets with an image, I found what appears to be a really useful forum post here: How to replace List Bullets to custom icons (SVG)