Students are normally 16 when they start 1ère and 17 when they finish, but he could have had to repeat a year, particularly if his native language is English (he claims to think in English); redoublement is not uncommon with students whose level of French is not considered adequate and perhaps this was the case when he was younger. Or he could have been placed a year behind his age group when he entered the French system.
The conditionals are surely reporting what he claims is currently the case and are neither conditional nor future in sense. He is (he says) currently in 1ère. The tense usage is as in this document from Luxembourg, dated 2016:
"A cet égard, il explique qu'il serait scolarisé au Luxembourg, pays où sa famille séjournerait depuis le 23 mai 2011. Inscrit au Lycée Michel Lucius, il serait un bon élève, qui serait apprécié tant par ses camarades de classe que par le personnel enseignant"
http://www.ja.etat.lu/35001-40000/36348.pdf
This is sometimes called the "conditionnel journalistique", I believe. The sense is "allegedly".