Just a few things

[khatchad]

I was missing authors in my output as I had a separate authors.tex file (you can do that in authorea by selecting customize). Also, my abstract already had the latex commands.

[eteq]

Thanks @mattpitkin - I'd noticed the authors option and been meaning to do something like that but hadn't found the time. I've left a few inline comments about the implementation that you'll need to address before I can merge, but it looks good in concept.