Display post’s description and caption

Something like this should get you close (untested):

<?php
    foreach($my_posts as $post){
        $thisPostId = $post->ID;
        $thisPost = $get_post($thisPostId);
        $thisPostTitle = apply_filters('the_title', $thisPost->post_title);
        $thisPostThumbnail = get_the_post_thumbnail($thisPost);
        $thisPostContent = apply_filters('the_excerpt', $thisPost->post_excerpt);

        $data[] = array(
            "id" => $thisPost,
            "title" => $thisPostTitle,
            "image" => $thisPostThumbnail,
            "content" => $thisPostContent
        );
    }
?>