I would like to know if there are any NetApp exporters / monasca-plugins which help me monitor Cinder storage ( free storage / Free storage per cinder backend / volume count by status per cinder backend )
I don't think this is the right place for your questions as this is the OpenStack community and the question isn't really an OpenStack issue. To get best support from the community i advise that you move your questions to the related discussions.
As NetApp is my storage provider, i would like to know if there is any openstack table on the whole which will help me monitor cinder ? i can find sizes for volume, backup, snapshots, etc but i want to know if there is a way to address the below queries :
There are no special database tables that get created when you use NetApp driver not any driver. there is no special table to extract data from. You might though fetch the created cinder volume types from the database like NFS, FC, ISCSI, etc and then monitor the backend volumes at the NetApp as you usually monitor volumes at netapp. Nothing is specific for using cinder as a client. For example at the openstack side you might see space available but at the netapp side your aggregate is full.