I live in the Southern Hemisphere. Can Classical Feng Shui be applied here in Australia?
Yes, without modifications. It appears that the Later Ba Gua, for example, must be modified. It appears that it does not make sense to have the Fire Palace in the South and the Water Palace in the North down under. Down under, the South is cold and the North is hot. It appears that the Fire Palace is to be located on the north while the Water Palace on the south. If you remember that energy comes from all over the Universe, and that our Sun is only a small part of it, then it does not matter where on earth you are, the same kind of energy comes from the same direction. In other words, the same method that we use in the Northern Hemisphere is also valid in the Southern Hemisphere. See Feng Shui for Southern Hemisphere.