Does a multicast receiver need an ip address to receive multicast traffic?
Can I just leave my NIC's ip configuration blank?
IGMP is an IP protocol, just like ICMP, meaning it will still have the IP header with source/destination etc.
I think you might be confusing the main feature of IGMPv3 which is SSM or Source-Specific Multicast. This allows an IGMPv3 client (i.e. your PC) to specify a source that it wants to receive a stream from.
Very basic description but a quick google brings up http://www.cisco.com/en/US/docs/ios/12_1t/12_1t5/feature/guide/dtigmpv3.html which will probably explain it better than I ever could :)
Hope this helps