Very broad questions indeed, but I think all of those you should start with IBM teams. You should be aware that it is a big change in terms of underlying technologies (ICP is designed for cloud native deployment, so your admins should be trained with new concepts such as Kubernetes, Docker, etc). As far as Pega is concerned as long as your pega container runs on a supported platform (e.g., Websphere - check the platform guide on the pega community site), it should work. Pega's own container deployment only supports tomcat at the moment. If you run ICP, you obviously need license from IBM in addition to Pega license.