I would like to place the caption text layer outside and below the slide show. If placed at the bottom the nav buttons are in the way and caption is obscured.

Hello Daniel,

As for now such an option to take the caption out of the gallery is not present. You can fake something up using a hidden absolute divs and using the Behavior Connector to apply show element behavior on "The image is displayed" event of the gallery. If you like to get more information on how to set this up, please, note that here.
The other possibility is to remove the buttons - here you can find an FAQ on how to do this: www.dmxzone.com/go?14108

Regards,

Miroslav

I would like you talk through the 'show the title/description using hidden divs' method, as some of my descriptions have over 1,000 charachters and completely cover the image. Or otherwise, how do I increase the height of the gallery so the description can happily sit above the image?

Doing CSS Image Gallery Description to be set in a custom DIV container:
1. once you create the gallery create a single div with ID in your page.
2. for each image in gallery apply a behaviour through the Behaviour Connector, named Set Tex -> Set text in Container
and there enter your description for each image.

That is all...