Unlike John, I don't have a working demo of this particular smaller idea, but as it relates to the styles/commands question, I thought I'd mention it.
So the idea is to use the style completion UI to show the user what the options are, by including the export preview; for the tex export processors, it would be the latex commands, and for CSL, would be the rendered output.
While I don't have it running, this should definitely be doable.
I put an initial mockup here.
Probably something like this should be added to oc-basic at some point.