Open Stack

I guess this is the default driver that openstack configures. I am working on creating a volume controller for our storage array and discovered some serious limitations with this driver. Apparently the driver only allows mapping one and only one iscsi lun to a hypervisor, which means only one lun can be mapped to any vm on the hypervisor. So few questions around this driver. 
1. I am pretty sure I am missing something, otherwise it is definitely a serious limitations. How do I overcome this?
2. This driver only allows lun to be mapped in a pass thru mode: the lun first need to be mapped to hypervisor and then to the vm. This is obviously very limiting to vm's mobility. How do I map the lun directly to vm? Obviously it can be done by discovering luns from the vm itself. It there a driver that accomplishes the same from the dashboard. Perhaps libvirtnetvolumedriver?
3. How is nas device provisioning supported by openstack? Is there a driver interface that is similar to iscsi driver that third party vendors can plug in their offerings with openstack?

Your quick response is much appreciated.

Thanks,
Murali Balcha