1) Assuming bus instances are configured to use MSMQ transport and are using multicast. Machines with multiple NICs (either hardware or virtual devices) need to have MSMQ binding configured in the following way :
At the registry key [HKEY_LOCAL_MACHINESOFTWAREMicrosoftMSMQParameters]
At the end the registry entries should look like this :
References
Confirmed to work in Windows Vista SP2 and Windows Server 2008 R2 environments