can completely unregistered user create content on a form and submit it for admin to review?
Like a simple contact form ?
I read a tutorial about guest registering into a "guest account" but this is not what I want.
I want really the user getting on the form for the first time ever, and submitting it without any registration.
The Meta Box plugin only helps you to create the fields, save the input and display the output easier. If you want to resize/optimize the image automatically, please follow this article to get a plugin to achieve the goal.