often other planes as well" im digging out my copy of the manual atm, hoping for a diagram, but its not completely necessary...
these other planes, can you see them from the ether like you can the material? since the material plane is 4 dimensional, i assume that it takes traveling in a 5th dimension to get from line of sight w/ prime to line of sight w/ x.
if you can see some of these other planes, and do not have to travel to go see them, then you can see them at the same time as you see the prime? thats gonna get confusing.
how about air, you can breath on the ethereal right? is that the same air as the material? if i blow a balloon on the ethereal and take it to the prime and deflate it, does pun pun show up and smite me for polluting.
assuming the air is normal, you can make a fire on the ethereal, assuming you brought fuel. say that fuel is lamp oil, you pour some out, into a floating sphere (pouring should be a trick because you should need gravity to help) (while still on the prime you filed a water skin w/ lamp oil, cause you knew what you were doing ahead of time...) ok,, so you squeeze out a sphere of oil into the ethereal and ignite it, th outside edge catches fire and glows like a star? cool. that would be cool to throw an infinite distance... you could mock up a model of the solar system, except without actual orbits, that would require gravity and the model would fall on the floor.
thats it for the basics...
how about creatures that are native to the ethereal. take a ghost for example. they can manifest them selves on to the material anyway, but how about if they cast blink, or ethereal jaunt, or travels through a portal to the material, or the astral or the some non coexistant plane.
or blink dogs, if you take a blink dog to a non coexistant plane, can they still blink? are they still a dog? no wait, they probably are still a dog, but very smart dog.
ok, im gonna go finish looking for my manual of the planes, talk amongst your selves.