Using a virtual machine as a network tap on a mac server
In bridged mode, the VM's port gets its own Ethernet MAC address. If VMNet acts like a switch, you might not see packets destined for the Mac's network node, which I assume is the point of this exercise.

Yes, the virtual port needs it's own IP address as well.

Internet sharing just passes along traffic not destined for the machine that is sharing. It is not a network bridge (it runs as a NAT IIRC), so it won't pass along broadcasts either.