1&2. You can use this CSS code below and put them on the Additional Style and adjust the color value:
3. We use a custom icon for the review. You can edit those icons on this file wp-content/plugins/jnews-review/class.jnews-review-frontend.php then jump into line 376 (for the pros icon) and line 400 (for the cons icon).
4. May I know what the current version of JNews Review plugin that you use on your website? Also, it would be better if you can provide your website URL so i can check it directly on my side.