In answer to your questions:
1) In the ClassiPress admin settings, you can rename the default custom post type and taxonomy URLs as seen
here, however you cannot remove it completely in here. This would require customization on your part.
2) As above, this would also require actual customization as the theme makes use of custom post types for ads and ad related URLs.
3) You can set the number of images which can be uploaded from within the ClassiPress admin, with the default maximum being 10, but these are still selected one by one.
4) There is no option for this currently within the theme, however the main index page has tabs for "just listed", "most popular", and "random".
5) Users can select the specific category or subcategory from the main category dropdown menu and it will then only display what they select.
Ultimately much of what you have listed would involve customization as they are not default theme features. ClassiPress is not encrypted, so you are free to modify it as you wish. AppThemes does not offer customization services, however we do have a
certified partners page where you can find developers for hire who are experienced at working with our themes. Thanks.