Deploy Kubernetes on OpenStack

1, 2 and 3 are correct.

Self-healing

You can deploy in master HA configuration. The recommended way is either 3 or 5 master with a quorum of (n + 1)/ 2

Can Kubernetes reprovision/restart some the failed nova instances?

Not really. That's after nova to manage all the server services. Kubernetes has an OpenStack module that allows it to interact with OpenStack components like create external load balancer and creates volumes that can be used with your workloads/pods/containers.

You can either use kubeadm or kubespray to bootstrap a cluster.

Hope it helps.

If you want to deploy Kubernetes on top of Openstack I would recommend that you look into Openstack Magnum. This is the most common use case for Openstack and Kubernates.

There is also the possibility of running the Openstack Control Plane under Kubernetes, which would allow you to better scale and auto-heal Openstack services. This is primarily for the Control Plane (e.g. nova-api), and as far as I know there is no way of running nova-computes under Kubernetes.

I found a good blog post here that describes some of the benefits from such an approach.

Yes, you're spot on with your observations in the case of running Kubernetes on top of OpenStack and the other answers here give you further pointers already. I just wanted to point out, in addition, that the other way round is also an option, that is, running OpenStack on top of Kubernetes, for example using OpenStack-Helm.