Hi David,
1. Usually this issue is caused when a custom field is not present on the result, that is present within the filter. Try turning on this option, if any of the fields was missing, that should resolve it.
2. Do you mean, when you click on the result? That is not controlled by the plugin. The plugin only redirects to the result, the rest is up to the theme, or the page builder you are using, if any.
3. If you have the latest release installed (4.15.2), then there is an option to add option-groups for drop-down and multiselect filters. There is no other builder available for it unfortunately.