Hi @janjawat1
1) Yes, the majority of custom fields can be searched via the search forms add-on.
2) In order to add more content to the listing’s cards, you will need to modify the template files https://docs.posterno.com/article/545-templates-customization
3) The plugin does not provide a sidebar. If your theme provides one, you can add widgets to it. Most of the times you may need to use a third party plugin to create a sidebar specific for the listing post type.