Even though I do believe a person's consciencness, or soul, lives on after death, I don't believe they can be communicated with. At least not as your sister describes. Trying to be a medium is dabbling in the occult, and I would stay as far away from that as possible. I've heard it preached by more than a few ministers that when mediums seem to be communicating with the dead, they are actually communicating with demons pretending to be the dead person.

As far as creamation vs. burial, I personally prefer cremation. But that's only because it's cheaper and I see no reason to waste more money than necessary to dispose of what I consider an empty shell. But I personally wouldn't want someone to keep "a piece of me" after I die to try to communicate with. That sounds a bit creepy.

Dakota