BuddyPress.org

@arturdesign2devcom I see CATEGORY, GROUPS, and SINGLE WP

So I see using http://buddydev.com/buddypress/blog-categories-for-groups-plugin/ where each group is a category. Create posts via front end; then create a regular category template file (see WP codex) for each group with the layout you want which can pull in the first image from the post in that category template file (get the image plugin or use post-thumbnail support).