

Debian Stable. Get it installed, get everything working right and configured the way this person likes it on a reasonable DE with default themes, and more likely than not, you won’t have to touch this thing for years.
The setup’s not necessarily for noobs, but if you’re the one doing the setup, you should be able to get it into a place where it will pretty much never break for them.
You should probably give them KDE or GNOME (probably KDE, as it’s more Windows-like and less my way or the highway than Gnome). As much as I love XFCE, it’s probably a good idea to give a layman a feature-heavy DE so that nothing is likely to be missing; also, it’s way too easy to accidentally delete panel items or entire panels on accident and a little annoying to restore things back to the way they were. KDE’s panels implementation mitigates these issues.
This should just be working if it’s standard USB audio; I’d recommend just researching issues with USB headphones in general. Maybe also try another cable.
If nothing works, it looks like you can use a double 3.5mm cable on this model, which pretty much every large retailer with an electronics section should have.