How should start of NBU service be configured in a cluster

Normally services configured in a cluster are disabled in rc scripts, but if NBU service is disabled, then you can't backup the inactive node, so I have the following queries:

1. When NBU master is clustered shoud the NBU service be started using rc scripts or only started by cluster.
2. When NBU master fails over it shuts down master server, but should it leave NBU client process running?
3. If NBU client is started on inactive node, will VCS be able to successfully fail over to that node or will the NBU agent fail to start NBU as a master as the NBU client process is already running 

Note I have asked this question in NBU forum as the VCS NBU agent is supported by NBU, rather than VCS

Thanks

Mike