For first and second statement, Yes. Please refer to below KB.
3) No, it does count against limit with VDS and vCenter since adding multiple ephemeral port push toward vCenter maximums. This limit is 1016 ports. For vSphere 4.x, 5.x limits you have link below and for vSphere 6.x please refer to https://www.vmware.com/pdf/vsphere6/r60/vsphere-60-configuration-maximums.pdf
Ephemeral binding
In a port group configured with ephemeral binding, a port is created and assigned to a virtual machine by the host when the virtual machine is powered on and its NIC is in a connected state. When the virtual machine powers off or the NIC of the virtual machine is disconnected, the port is deleted.
You can assign a virtual machine to a distributed port group with ephemeral port binding on ESX/ESXi and vCenter, giving you the flexibility to manage virtual machine connections through the host when vCenter is down. Although only ephemeral binding allows you to modify virtual machine network connections when vCenter is down, network traffic is unaffected by vCenter failure regardless of port binding type.
Note: Ephemeral port groups must be used only for recovery purposes when you want to provision ports directly on host bypassing vCenter Server, not for any other case. This is true for several reasons:
- Scalability
An ESX/ESXi 4.x host can support up to 1016 ephemeral port groups and an ESXi 5.x host can support up to 256 ephemeral port groups. Since ephemeral port groups are always pushed to hosts, this effectively is also the vCenter Server limit. For more information, see Configuration Maximums for VMware vSphere 5.0 and Configuration Maximums for VMware vSphere 4.1. - Performance
Every operation, including add-host and virtual machine power operation, is slower comparatively because ports are created/destroyed in the operation code path. Virtual machine operations are far more frequent than add-host or switch-operations, so ephemeral ports are more demanding in general. - Non-persistent (that is, "ephemeral") ports
Port-level permissions and controls are lost across power cycles, so no historical context is saved.
