I find the advice on prefixing atom names with * very useful, especially for Clojurescript / Reagent code. I have never encountered such style before though - is it a widely accepted convention?
I have seen some Common Lisp code which also uses that notation. Of course it could have been CL code written by a clojurian;-)
I haven't seen it. I don't find myself using atoms very much and when I am using atoms, it's almost always because I'm trying to use doseq when a more functional version of my code exists if I would think about it.
From my experience, atoms are indeed rarely needed on the backend, where you have a DB to store the app state, but you can't do pretty much anything without them in cljs / Reagent.