WMG / Assassin's Creed: Embers

Subject 16 has relived Shao Jun's memories
Lucy mentions he lived the life of an ancestor in the Far East, and if you read the blood wall above Desmond's bed, there are multiple Chinese sentences and even an explicit reference to Emperor Jiajing.

The young man at the very end of the film was a figment of Ezio's imagination
Think of him as an apparition of Death, in the shape of the personality of Ezio's younger self, telling him his life is coming to an end.

What Shao Jun and Flavia were talking about
Shao Jun noticed Flavia hiding from her father and how she peaked her head up and down while giggling, and gave her tips on how to better conceal herself. They're going to practice with hide-and-seek because her father is busy at the moment.
http://tvtropes.org/pmwiki/pmwiki.php/WMG/AssassinsCreedEmbers