Yes, and Elkayem’s earlier DIN MIDI to CV, which is what my MCVI is based on, does make use of that (that’s the “different modes of the DAC (selected by the software)” I mentioned) in addition to different output gains.
My understanding is that pitch differences of 3 cents are the limit of what a trained ear can distinguish, so I’d call it definitely acceptable. (Though even smaller pitch differences can lead to audible differences in beat frequencies between two notes played simultaneously; if you’re worried about that, then you need probably at least 16 bit resolution.)
Right, and there was some discussion of that elsewhere. In principle, you can map the nonlinearity of a particular DAC and correct for it in software. Something I want to consider for MCVII. (In fact you can even map and correct for the nonlinearity of a particular DAC/VCO combination, if you want — compensating for VCO nonlinearity too.)
Add: Also, as pointed out here, if you pick just the right voltage reference value for the DAC, it’s possible to get 0 cents maximum resolution error (for MIDI notes, not for arbitrary pitches)! You lose about half an octave of range if you do that, though. And it probably doesn’t work with nonzero nonlinearity. Not really worth it.