Short answers, pulled from the story.
Walloon belongs to the langues d'oil family, the same branch of Romance languages that includes French. It descended from Vulgar Latin and is distinguished within that family by archaic Latin features and extensive borrowings from Germanic languages including Dutch and German dialects.
In 2007, the number of people with any knowledge of Walloon was estimated at 600,000. The vast majority of fluent speakers are aged 65 and over, while those born since the 1970s typically know only a few idiomatic expressions.
Walloon declined primarily because France's annexation of Wallonia in 1794 established French as the language of social advancement. After World War I, public schools taught exclusively in French, and official orders in 1952 directed schools to punish students who used Walloon on school premises.
The four main dialects are Central (spoken in Namur, Wavre, and Dinant), Eastern (spoken in Liege, Verviers, Malmedy, Huy, and Waremme), Western (spoken in Charleroi, Nivelles, and Philippeville), and Southern (spoken in Bastogne, Marche-en-Famenne, and Neufchateau in the Ardennes).
Walloon is spoken in a small area of northern France around the Pointe de Givet, and in communities in Door County, Kewaunee County, and Brown County in Wisconsin, United States, owing to large-scale Belgian immigration in the 19th century.
Walloon was formally recognized in 1990 by the French Community of Belgium as an indigenous regional language that must be studied in schools and encouraged. The Walloon Wikipedia launched officially in 2003, further supporting its use in large-scale publication.