Need help knowing what these things exactly are and why or if, the Church opposes any of them (or all of them) - just don't know enough about them and am being questioned about it. God bless you all for any help!
All three are bad. There might not be anything Pre-Vatican II that mentions those three by name, but you will find these things are mentioned based on what they are: spiritualism and superstition.
Reiki is calling on a power (yourself and indirectly the devil) to heal someone. You call upon a power (mentally) that you do not have (beyond your natural human faculties) to heal someone. Usually accompanied by a ritual, such as moving you hand over the body part. Thus, you become the instrument for this unknow power to channel through and effect the subject you are trying to heal.
Look up Church teaching against spiritualism and superstition.