Hi,
1. Those might be results not having any of that taxonomy. You can turn them off by this option: https://i.imgur.com/M0IslWO.png
2. Because the results are a “div” HTML element, and have event handlers attached to them to handle the clicks. Right click will work with the vertical/horizontal result layouts, but this isotopic layout has more complex functions.
3. Well, you can either use the advanced title/content features to add custom elements, as well as the results templating if needed. I only recommend doing a pop-up feature if you have extensive knowledge in custom coding, especially javascript and HTML, as event handlers have to be adjusted.
