Thank you once again, gentlemen, you have been very helpful.
Seems like I will use the Cubase Control Room for Listen Bus, and TotalMix FX for zero latency tracking w/ reverb for singers.
Not sure if “Cue” mixes in Cubase (formerly known as “Studio” mixes), or routing w/ TotalMix FX to achieve the same effect will be better.
Now I have to figure out what to disable or leave enabled in my F4 Cubase VST outputs. Aaargh! 
Thanks again -