Is the Q-Slider output suitable for controlling the CV input of the A-130-8V in this way?
I don't know of the module's output voltage but I'd say yes, it looks like it should be working flawlessly
Would this give me a useful and reasonably smooth range for manual volume performances?
Again if both modules share the same vlt in/out, nothing to be worry about
Are there any problems with using the Q-Slider's M-IN / MAX settings to calibrate the VCA range?
Does anyone use a similar setup in practice?
No, not at all, it is the purpose of VCAs
Lets wait for another/more experienced user than I am to input his words...
If you need help with a module I own/sell, I'll be happy to help, don't hesitate!