I got all answers... For the benefit of others who are searching answers for the same question:
1) I just downloaded the dcnm client for LAN ... is there a seperate client for SAN ? I dont see any download links for SAN... --- Yes .. DCNM SAN has a seperate client. After installation, you can open the DCNM page on http, and you would find the download links on top right corner for DCNM-LAN, SAN and device manager.
2) Is it possible to add brocade switches to DCNM-SAN? Does it require additional licenses? - I dont think this is possible
3) Can we use the fabric manager license "N5000FMS1k9" for DCNM SAN, or do we need "DCNM-SAN-N5K-K9" license for the nexus 5000? - Yes.. Use the same license and generate the PAK file. FMS licenses do work in DCNM-SAN..