In my PDF, a full-page image is followed by an almost blank page before the text continues. Is that intentional?

No, it was a bug, fixed in version 1.9.7. A full-page image that had a caption was given a page break twice, once for the image and once for its caption, which left the caption alone on its own page. Since 1.9.7 the sequence is: the chapter title page, the image with its caption on its own page, then the text. The chapter title standing alone on its page is intentional when the first element of the chapter is a full-page image, because the image needs a page of its own. If you prefer the text to start under the title, set the image's layout to "wide" instead of "full page".