As for adding captions, You could use photoshop or a program similar to it to add text captions onto your pictures you're using. You could also use the pictures on actual pages and have the whole sprout be a slideshow itself. Just put the pictures on a separate page and you can also add other assets or media onto your sprout.

You can also stop the autoplay for slideshows by choosing "on click" under the "switch after" section.

thanks fo the good ideas, much appreciated.