I'm sure more experienced members will chime in with some helpful hits, but to be brief and timely I will chime in with:
It is not necessarily required to report after the plant drop its blooms. The medium the orchid came was likely the medium the orchid grew its blooms in, so it's probably OK to keep the orchid that medium unless it looks very deteriorated.
It sounds like you may be potting your orchids too tightly. A tight potting keeps air from penetrating down into the center of the medium and without air there is no evaporation and good conditions for root rot. A tight potting is going to dry out on the surface while remaining soggy in the center. A good way to test if the center is damp is to wiggle a wooden skewer a few inches below the surface. If you pull it out and it is damp you probably don't need to water.