Hello,
Appreciate your job done writing this detailed description. There will be some questions, but task is clear in common.
I've been working with AWS since 2010, with its major service - S3, EC2, RDS, SES and others. I've been working with EC2 instances running Ubuntu mostly, but I've touched static sites on S3 either. I do know what is it, what is JSON-policy for S3 bucket and so on.
I'm very interested in your project and would be happy to create some elegant solution for your task.
Feel free to ask your questions.
And yes, I have my own AWS-account where I could work, of course.
Thanks, Alex