Persistent Storage with Docker in Production – Which Solution and Why?

Hello, I've recently started working for a company that wants to break their monolithic SaaS application up into containerized microservices. I'm having a hard time grasping a fundamental part of persistent storage, though. Why are there so many different competing platforms? Portworx, Rexray, StorageOS, Flocker, Inifint, etc.

My Questions

1. Why wouldn't someone simply spin up an NFS server and use a hierarchical folder structure there as their storage backend? What gains do you get when using one of these tools?

2. How dangerous is it to use something like this with Docker? What are the common causes for catastrophic data loss in a docker-based environment?

3. What persistent storage solution would you recommend and why? My company operates a SaaS platform. The data payloads are small in size (5kb-100kb). Data processing is small-medium in resource consumption. Overall volume is medium, but continues to grow. We're hoping to completely move our monolithic application to the cloud as separate containerized microservices. Including our data warehouse.

4. Somewhat unrelated, but it ties in. What are the strengths of using Kubernetes as an orchestrator as opposed to Rancher/Cattle? Isn't Kubernetes over-engineered for a small-medium sized platform? Are there any strengths to using Kubernetes in Rancher aside from the one-click installation?

Thank you for the insight. Sorry for the naivety. I welcome all documentation and supplemental reading material.

EDIT: For context we are using Azure as our underlying Cloud platform.