Group interview then personal interview, make sure you know about logistics and about history of decathon They are searching for young people, manly students, that are somehow connected to sports. So you should mention the sports that you are pratcsing

Normal, preguntas bastante comunes. Enfasis en actitud, poca información respecto a sueldo y condiciones. Parece que el trabajo se adapta a ti una vez te seleccionan, con lo que trabajes, demanda, carga de trabajo etc