Who is he? Which country did he hail from? What's his name?

Google "youngest pope" there's a ton of hits.

Even wikipedia has a section from which you can follow links to more information:
List of popes - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/List_of_popes#Youngest_popes)

I guess its sort of a toss up because accurate early records were not kept or lost. John XII (955-964) is believed to be the youngest pope in history, elected at approximately 18 years of age, according to Encyclopedia Britannica. I don't know which country he was from.