Most people here have a lcd screen / lcd touchscreen for display.
To be honest.... if you want a headless unit.... and you just want it to play music...
Why not just buy a 'normal' headunit that can play MP3's? There are several that will play MP3's from CD, from USB device, and even a couple which have a built in hard drive.
Saves you a lot of work and extra expenses/configuration of running a computer in your car, if all you want is music playback.
If you eventually plan to have a full-fledge carputer to do more then just music.. I would suggest a cheap headunit like I mentioned above, and then invest in the carputer setup over time.