The lowest cost option would be vSphere Replication. This is included with vSphere Essentials Plus licensing and higher. Keep in mind that recovery will be a manual process (recovering each VM individually) and there won't be any way to non-disruptively test your recovery. You would need to purchase a vCenter for the recovery site as VR is dependent on VC so you wouldn't want to be using a single VC.
I'm not sure what you mean by Replication/HA as an option. In the context of vSphere Replication and HA are two very different solutions. vSphere Replication (VR) is a per VM, host level replication solution. HA is a cluster level solution primarily for recovering VMs after a host failure, unless used with stretched storage and vMSC it is not a DR solution. The two solutions do interoperate (a HA protected VM can be replicated).
You would need to license your hosts at the recovery site for this to work as the VR VMs and the vCenter will be running at the recovery site.
I don't believe that stretched cluster will be an option for you as I don't believe it is something that PowerVault supports. There is also the question of latency requirements (5ms RTT max) and cost (stretched solutions are usually a lot more expensive - other than vSAN). If you want a vSAN stretched cluster for this environment (assuming you meet the requirements) you would need a vSAN license, otherwise not.
Not sure what exactly you are asking about regarding windows licensing. You are possibly better off asking MS or posting it to a VMTN forum that discusses those types of questions.
I also want to point out that these are not your only options. If you aren't concerned about manual effort or recovery time you could always backup your VMs and replicate your backups to the recovery site. Depending on the backup solution this could require a minimum number of vSphere licenses (assuming they can be moved from protection to recovery when needed) and no VC license for the DR site. The RPO and RTO for this option would correspondingly be much higher than the other options.
