>>First, days on Earth were not always 24 hours. How do the authors of the account in Genesis know that when these events occurred (after all, they were NOT a firsthand account) were 24 hour days or not?<<
So if the days of creation were longer then 24hr days did they change immediately after Adam was created to make the number of years he lived correct? Or is the Bible wrong as to how long he lived?
I could not tell you but I would imagine that distracting ourselves with such details detract from us learning about the consequence of Adam not stopping Eve from being tempted.