You have things, pretty much, correct. However, if your processor/receiver has a global fixed crossover frequency (one frequency crossover point for all speakers - probably 80Hz), I recommend setting all your speakers to "small," even the M60s.
If your processor/receiver has programmable crossover points, allowing you to select different crossover frequencies for each individual speaker, I'd still set all speakers to "small" but I'd experiment with lower crossover point for the Mains, and perhaps even higher ones for the surrounds.
The frequency you chose should be based on the +/- 3dB frequency of each speaker. For example, the +/- 3dB point of the M60s is 37 Hz. You could try a 60 Hz crossover, to see how that sounds to you. I think a 40 Hz crossover would be too low, but you could give it a try.
The VP150 has a +/- 3dB point of 50 Hz. A 60 Hz, crossover might work, 80 Hz would be fine.
The QS surrounds have a +/- dB point of 95 -100 Hz. You could probably get away with 80 Hz, but you might try 100 Hz to see if you prefer that.
I had a receiver with a global crossover point of 80Hz, and enjoyed the results just fine with M60s/VP150/QS8s. YMMV
