Man, you are most welcome.
Regarding having the database distributed on 4 3TB LUNs each for a MS-SQL node, i think it could be supported by Microsoft to distribute the database on multiple disks.
Check this Microsoft document : Using Files and Filegroups
From my experience, i see many people deploy Microsoft clustering as follows :
A Microsoft cluster with 2 nodes, one active and one passive both are pointed to one or many shared physical RDM LUNs.
Regarding the NBL, I have found this document from Microsoft which states Network Load Balancing should not be used to directly scale applications, such as Microsoft SQL Server™ (other than for read-only database access), that independently update inter-client state because updates made on one cluster host will not be visible to other cluster hosts. To benefit from Network Load Balancing, applications must be designed to permit multiple instances to simultaneously access a shared database server that synchronizes updates. For example, Web servers with Active Server Pages should have their client updates pushed to a shared back-end database server.
Network Load Balancing Technical Overview