Please find the right steps
Query1
before activity take VM export which are stored on datastore
Home => datastore and datastore cluster => select the datastore => VMs => add all the columns => take VM export
take latest RVTool export.
shutdown all VMs => Unregister all VMs and Templates => RK on Cluster (edit setting => datastore hearbeating => here we have to select another datastore and click on OK)
to confirm new datastore is visible as datastore heartbeat select Cluster=> Sumamry => Custer Status => Heartbeat Datastore )
if we are able to see new datastore then now remove old datastore from datastore heartbeat
RK on Cluster (edit setting => datastore hearbeating => here we have to uncheck datastore and click on OK)
unmount => detach(need to perform this step on all esxi host) => san team will unmap => start storage movement activity (poweroff storage) => move the storage => poweron => san team will map the datastore =>attach((need to perform this step on all esxi host) => mount the datastore
Register all VMs
Poweron All VMs if get message (moved it or copied it ) select Moved it.
Query2:
it won't throw any error, will work seemlessly.
Query3:
Yes we need to unregister all VMs and Templates before unmount a datastore.
regards
Mr VMware