Hmm, tough one.. Let’s see if it’s possible..
1. Add a new post – set the “Featured Image” – this will be the image in the excerpt that links to the post.
2. Add your page header with the link to the full image. – this will be your featured image on the single post page.
As for opening it in a lightbox, you could try using Jetpack’s “Carousel” module, but I’m not sure if it lets you choose which images to open in a lightbox.
Worth a try – let me know how it goes 🙂