Hi There @MarcKara
Thanks for writing in! We have a migration guide on our knowledge base section. If you follow our migration guide here (https://theme.co/apex/forum/t/cornerstone-content-builder-migration/126), your site should function properly after migrating.
In terms of site validation, you simply need to assign the site URL to your account and use the license key to validate your site. Please follow our product validation guide for more information (https://theme.co/apex/forum/t/setup-product-validation/55).
Basically we recommend the following configurations on your server to avoid incompatibility issues.
PHP version: 5.6.x or later version like 7.1.x (avoid the latest version 7.2.x as it may not compatible).
PHP memory limit: We recommend 512MB or higher.
PHP max script execution time: We recommend the value 120 or higher value like 300 for max_exection time.
With regard to building the AWS instance, it's better to contact a hosting expert if you don't have the required knowledge.
Hope that helps.