I don't have much experience in growing Spath. In Philippines, we plant them on the ground ( use them as borders) and they don't require much attention. Here in Hong Kong, I grow them in pots using a mixture of peat moss and bark. I water them before the medium get completely dry, but thats not always the case in summer because they are growing outside and well, when it rains they get wet. In winter, I protect them from the cold and the occasional rain. They seem to go into some kind of dormancy, (I'm sure this does NOT happen inside a warm g/h but this happens if the plant is left outside in winter) take care that the plant does not loss all its leaves during this time. If this happen, you are left with just the bulb and that bulb will not grow leaves again, instead it will produce shoots and you have to wait another year for the new growth to mature.
They can take direct sunlight. In fact, they seem to have more flowers if they are under direct sunlight at least half of the day.
I have never grown this plant from seedling, but I'm sure someone else would share what they know.