I would not put it that way. You cannot really practise Reiki wrong, unless you are following some rule that makes no sense, like being told you cannot practise while wearing black. Remember that you are Reiki and you are in Reiki, and the practices are there to help you let go into that experience.

Call it what it is: a meditative practice. Most people understand meditation today. In the Japanese practice the foundation is Hatsurei Ho, which is meditation, and the space we go into when giving a treatment is the same space we go into sitting alone. So you can say to a sceptical relative: I go into a meditative space, and you come into it with me. You are helping them to meditate.

Yes, unless they are too young to understand what is being taught. Mikao Usui said in the Japanese manual that everyone can learn: children through to old people, anyone with the capacity to follow the teaching. What matters after that is going away and practising on yourself.

When people apply for Shinpiden+ they very often say they want to go deeper. Deeper into what? Into ourselves. Not by adding more techniques and practices from outside, but by using the tools the system of Reiki already gives us, from a Japanese perspective, to find out who we are, why we practise, and what each practice means to us.