Hello,

- Is there any license required for operation manager. 

Yes.  I suggest you engage your local Cisco representative for how to purchase.

- Is there any license required for Media server.

Yes.  I suggest you engage your local Cisco representative for how to purchase.

- Is there any license required for third party cameras

Yes.  I suggest you engage your local Cisco representative for how to purchase.

- Can we enable media server service in the same operation manager VM. (like without adding new VM for Media server)??

Yes, it's what's referred to as a 'co-located' server, and it's easiest to enable both the roles when performing the initial setup of the VSM installation.

-  What is the minimum space required for video recording.

While there technically isn't a 'minimum' for archive recording, I wouldn't recommend starting with less than several hundred GBs of storage within the media repositories.

There is a lot of information to consider... so I suggest you check out the following resource map:

http://www.cisco.com/c/en/us/td/docs/security/physical_security/video_surveillance/network/vsm/roadmap/vsm_7_roadmap.html#pgfId-48992

Cheers and best of luck!