Mesh independence, yes, but if you plot contours with node values off you can usually get a good idea if you're resolving everything (phase, velocity, temperature & pressure) sufficiently.
Apect ratio is a difficult one. If VOF is flowing along the cells and you have ripples/waves then it needs to be fairly low (you need to resolve the flow along the wall as much as you do towards the wall). If there's no VOF free surface then the usual rules apply.
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