I'm trying to use Kubernetes to manage a scenario where I need to run several instances of an application (that is, several Pods). These are my requirements:

1. When I need to scale up my application, I want to deploy one single Pod on a specific Node (not a random one).
2. When I need to scale down my application, I want to remove a specific Pod from a specific Node (not a random one).
3. When a new Pod is deployed, I want it to mount a specific PersistentVolume (not a random one) that I have manually provisioned.
4. After a Pod has been deleted, I want its PersistentVolume to be re-usable by a different Pod.

So far, I used this naive solution to do all of the above: every time I needed to create a new instance of my application, I created one new Deployment (with exactly one replica) and one PersistentVolumeClaim. So for example, if I need five instances of my application, then I need five Deployments. Though, this solution is not very scalable and it doesn't exploit the full potential of Kubernetes.

I think it would be a lot smarter to use one single template for all the Pods, but I'm not sure whether I should use a Deployment or a Statefulset.

I've been experimenting with Labels and Node Affinity, and I found out that I can satisfy requirement 1, but I cannot satisfy requirement 2 this way. In order to satisfy requirement 2, would it be possible to delete a specific Pod by writing my own custom scheduler?

I don't understand how Kubernetes decides to tie a specific PersistentVolume to a specific PersistentVolumeClaim. Is there a sort of volume scheduler? Can I customize it somehow? This way, every time a new Pod is created, I'd be able to tie it to a specific volume.