First of all, there are only a few additional elements available, second, this is not recommended. I already spent a lot of time formatting some elements that could find space in some of the layouts, across multiple screen sizes, considering the output may differ lot from image to image also. For example, EXIF (class .exif) is available, but you could only fit that into blocks layout if you remove dimensions and file size, and only in cases where model name for example does not exceed the size of the block. Furthermore, you would need to stack EXIF values on the same line (wrap), as there is definitely not room for all exif items on new lines.
Keywords does not exist, because it can be long, and there just isn't room for it. Headline is already included, if exists in the image.
Sorry, but this is not useful. If you want to edit some features, that's up to you, but I don't recommend it, and I don't support it, and there are only some hidden elements available.