Please see this: Why is my Header Image not showing on Single Posts?
Regarding moving the post date: You’ll need to modify the theme files to do this. I recommend starting with a Child Theme to make the modifications, so that your changes don’t get overwritten by future theme updates. You can read more about customizing via Child Themes here.
If you’re not sure what exactly to customize or if you’re not comfortable with PHP/WordPress code, please post a question on the WordPress.org Support Forum, as there are many volunteers there willing to help. 🙂