Hi!
1. Well, this is not really related to the plugin, as the overlay is managed by a custom script. but there is an option that may help. Try enabling this: https://i.imgur.com/0kwMNQx.png
Then the plugin will try to detect if it gets invisible, and close the options/results if so. It may not work in some cases, as it should be resolved via the custom script.
2. Might be possible with a custom code.
Try adding this custom code to the functions.php in your theme/child theme directory (copy from line 3 only!). Before editing, please make sure to have a full site back-up just in case!
3. I will have to test this until the next release. Firefox may have changed how triggers work for the right mouse button. It should be automatically cancelled by the browsers, but I guess they changed something. Anyways, thank you for letting me know.