I am ready to do the work for you, as I'm familiar with adding articles to WordPress websites and blogs (as I worked as a link builder some time).
So, I will provide you with 20-25 added articles per day, this is up to 20 days for all 500 articles. If you need more (or faster) - we can discuss that.
I will check format, links and so on and I will add only relevant pictures. Also, you will see the progress in Excel Sheet with all the added articles and links to picture from a free stock.
If you have some questions - you are welcome to PM.
Anyway, good luck with the project!