Hi Oren,
1. As you told us in other support forum topic you are getting the in parent theme also not only in the child theme as well as your WP says that it is broken, so regarding this issue, could you please send us your site URL as well as the WP-login details of your site but please select the set as private reply before you click in submit.
2. You can use the following plugins for it;
- Contact Form 7
- Jetpack by WordPress.com
- SG CachePress
And for making your site same as demo you can follow this tutorial for it; https://www.styledthemes.com/documentation/pro-themes/corporate-portfolio-pro/
We hope this is helpful to you, if not then please let us know.
Thanks