Kubernetes version see kube_release variable in playbook.yml.
No dedicated master node - apiserver, controller-manager and scheduler are just another Kubernetes pod local to specified master instance.
No authentication to apiserver.
Cluster is expected to be run on a private network, apiserver will be bound to given kube_master_ip, ensure using firewall that only cluster nodes can access ports 8080 and 6443 on given IP.
If you need to access apiserver from outside world, add nginx with basic auth in front of it.