Yes the multitronic is a CVT box - even in the newest incarnation which always provides 7 ratios rather than the pre-2005 ones which behave more like a normal cvt.
I very rarely go into N - only for a very prolonged delay.
The drive chain is under very little load at this point - the CVT itself unlike a traditional torque-converter based auto has no inherent 'creep' whatsoever - the 'creep' that we all experience is actually electronic control of the conventional clutch, slightly and deliberately slipping it to simulate a normal auto creep.. done to keep traditional auto drivers happy.. so I would suspect that its actually wear on the clutch that is an issue rather than the chain and associated mechanism.. But this function was 'designed in' and the materials should cope with it. Audi provide no advice on this, and there are a lot of these boxes out there.. in fact the only advice seems to be oil changes at 40k - same as their normal autos!
cant comment on whether the repeated engagement of D-N-D etc would have an effect, I dont know.
my irritation is that for this programmed in creep to work, the clutch is already partially engaged.. so why does it take so long to fully engage when you actually go!