I use 2 tools to add articles (and categories) in bulk to Joomla.
OSContent by Joomlashack
https://www.joomlashack.com/joomla-extensions/oscontent/
CFI Plugin import/export Joomla by Joomline
https://joomline.org/extensions/scripts-other-developments/cfi.html
A simple overview on the basics of Joomla user group access.
A few months ago I explored doing a Joomla! Category List override to include custom fields on a client site. I thought it would come in handy for a client list as well to more easily manage notes/dates.
I was inspired from this post at Joomla! Stack Exchange.
Here is a video tutorial including all the steps: