1. The plugins you mention are created by different marketplace developers, with the features for each outlined on their marketplace pages
here and
here with screenshots and demo link available.
2. You could certainly make a main index page by which users can select the country first and are redirected to the relevant instance of ClassiPress for their location if you wanted to make this the primary feature. You could install various instances of the theme in subdirectories for each location, perhaps on a
WordPress multisite installation.
3. Yes, ClassiPress has a custom forms and fields functionality which will allow you to create specific listing forms based on the category selected. You can then also incorporate those custom fields into the advanced search.
4. This is not a feature of the theme, so it would require customization on your part if you were looking to implement this. Thanks.