Does Juicebox have a WP plugin?
Yes. WP-Juicebox can be downloaded from its support page here.
It is very similar to WP-SimpleViewer (the SimpleViewer plugin for WordPress) so if you have used WP-SimpleViewer before, it should not take you long to get up and running with WP-Juicebox.
We're proficient in HTML/CSS/JS. Would we be able to tweak the layout / template of Juicebox or would we be limited to the changes possible via those configuration options?
You would be limited to the available configuration options.
There might be complications that you would have to tackle such as the thumbnail display being responsive (the number of thumbnails displayed is partly dependent on the size of the browser window) and functionality such as auto-hide may complicate things further.
Juicebox would not know of any manual modifications and would expect thumbnails to be in a certian position and configuration. Because of this, manual modifications might cause unforeseen problems.
Also, the 'juicebox.js' file is packed and obfuscated so it would not be easy to decipher how Juicebox currently works.
Having said that, Juicebox-Pro is fairly flexible with regard to thumbnails. There are many available Thumbnail Options and several different thumbnail layouts can be found in the demo galleries. Check out the Hong Kong demo for big thumbnails, the Simple demo for a SimpleViewer-style layout and the Top-Left Alignment demo for a large number of thumbnails.
SimpleViewer Support Team