I haven't been able to find a good answer so far in googling around... what is you feeling about the effect of timelessness in some planes like the Astral Plane? It seems to suspend metabolism-like functions in the body, but what about spell durations and other time effects? As far as I can tell, those last their normal durations according to the rules (although on the Astral specifically, spells are quickened).
And while we're adventuring astrally, what happens when you take an extradimensional space into the astral or ethereal planes? Putting them inside each other opens various rifts to those planes, but do they have trouble being in the other planes?