Do we know around when Callisthenes' Deeds of Alexander was lost? How late did it survive?

Answer 1

We don't know for sure, but it was probably after 400 CE: https://www.livius.org/articles/person/callisthenes-of-olynthus/ (follow the links in this article for more information - you could also try searching the JSTOR database, which gives you a certain number of articles to read with a free account: https://www.jstor.org/)