No.
So you take a server and put a SCSI card in it....run a SCSI cable to an external SCSI drive.....Provision storage. Boom....you have storage.
iSCSI essentially replaces the SCSI card and cable (ie..transport)...that's all it does. Provisioning is still up to the server. So the NAS simply carves raw space and makes a target available. It's up to the server to format the target partition presented. After formatting, you create your folder structure, add NTFS permissions and shares.
It would flow through the server to the NAS.
If you have a NAS that does CIFS/SMB, you can possibly join it to a domain and provision the shares that way. There are quite a few that can do this. The iSCSI route probably is a little more powerful on the administration side, but will likely have a little extra lag due to network latency. If you can enable jumbo frames and keep the server/NAS on a single subnet with at least a gig link at full duplex, you'll see decent results.
If you have a lot of users, consider going big and up your spindle count. Dell MD1220s offer a SAS connected array with 24 or 25 drives, so you can do RAID10 or RAID6...you can support quite a few connections that way for relatively little money. Supermicro has similar solutions.