You can import the demo website data, we have a guide for this in Getting Started > First Time Setup Guide
You just need to assign the primary navigation - go to Appearance > Menus and set the Primary Navigation as the Primary Navigation
The demo website images are not included for copyright reasons, they are replaced by blank placeholders in the theme package
Make sure you've added your booking page URL in Theme Options > Bookings in the Booking Page URL field (this is the page with the [booking_page] shortcode added to it - if you imported the demo website data the page is named Booking)
A lot of web hosts and email providers block email sent using the standard PHP mail() function due to spam/abuse. The best option for sending emails is with SMTP, you can install the following plugin and enter your SMTP details in it to successfully send emails: https://wordpress.org/plugins/wp-mail-smtp
Go to WPML > Multilingual Content Setup in the Custom posts section set Bookings to Do nothing