Apparently the art book is just a compilation of pieces we've seen many times over.
Anyone want to confirm that?
It's a compilation of the artwork that's exposed at the exhibition. That includes many pages straight from the manga, the volume covers and some other color illustrations that are less common but have been published before. There might be some new pieces, but nothing concrete was announced in that regard.
Is the Guts image from the banner only referencing the skirmish, or would it have been directly used? I don't remember we've seen that image yet in manga.
I think it would have been used directly.