Just wanted to follow up in a separate thread that the DisplayPort adapter works, and I'm able to use XFCE Terminal with various command line goodies (git, ssh, vim) on an external display.

Next up: exploring alternate browsers in Libertine, perhaps cracking open a compile/build for Firefox, and looking for a Riot.im native app.

Thanks to @advocatux and the rest for help.

@advocatux I'm not in front of the Macbook right now, but I'll see what the logs say when I am, and I'll post here.