Thank you again Split, for a very helpful answer!
I’m using this more as an exercise in how to compress/limit … it’s just a rough demo of voice/piano. Your answer I think is giving me some nice insight into the process. Can I follow up with another question or two, Professor? 
^^ How do you determine whether “the peaks are near 0dB without limiting”? Listen for distortion, look at waveforms, use the “normalize” function, …? I did the latter (normalizing), but as I did, I was wondering if that was the right thing to do.
As the limiter just “starts biting into the peaks”, what would be the response of the gain reduction VU meter? Would it just start to become barely active, most of the time not moving because there are no peaks except rarely? I do hope one day to be able to tell this by listening only, but at least for now the VU meter is a handy tool for me.
Thanks again, Split!