Hi,
Answers Inline,
1- Its surly supported in 7200 to run multicast for vrfs.
2- Yes its possible with the command (IP multicast-routing vrf (Name) , this should enable Multicast for Only the Vrf.
3- Cisco recommends Implementing Source Specific Multicast to optimize Multicast traffic and supports higher bandwidth.
4- There is a lot of Security Recommendations when running Multicast, Here are some Notes to be considered:
a) Implement TTL Scoping for the multicast traffic.
b) RP Protection (Limiting Registration requests, Assigning particular Groups for the RP).
C) The RP Announce if Auto-rp is implemented should be limited using the Scope command.
HTH
Mohamed