Hello,
Thank you for your choice of our plugin. Regarding your questions:
1. You can read
here how to create/find Facebook app ID. This manual for "ARI Stream Quiz" plugin, but section about Facebook app ID is the same for "ARI Fancy Lightbox".
2. It is a bug, we will fix it in the next version of the plugin. Currently you can add the following CSS rule to "Custom CSS" parameter on "Style" tab to change opacity:
BODY .fancybox-is-open .fancybox-bg {opacity: 0.1}
3. The plugin uses data from titles from Media Library when the lightbox is integrated with WordPress native galleries (JetPack galleries). These galleries add data from Media Library to HTML code and then it can be used by the lightbox. The lightbox can also retrieve titles from EXIF data (if it is defined in image file).
Regards,
ARI Soft