Headscratchers / Dude, That's My Ghost!

• What are the chances of every member of the Wright family having a different hair color?
  • Jessica, at least, might be adopted. To say nothing of appearances, she doesn't act anything like scatterbrained Hugh and Jane or toned down but still sort of off Spencer. Plus, the rest of the Wrights seem predisposed to being passive(verbally aggressive being the typical end point, with Spencer especially) when she is clearly the opposite.
• Only people wearing Billy's stuff are supposed to be able to see him, but a bunch of people not wearing Billy's stuff have seen him.
• Minor one, but why doesn't Billy reveal himself to the rest of his relatives? Why just Spencer and Spencer's two friends? Obvious real reason is demographic appeal, but is there an in-universe reason?
• When Spencer is getting Billy to record a new single, how does the recording equipment pick up on Billy's voice? Prior to this episode, machines don't appear to record ghosts.
  • A little WMG, but since Billy was a musician in life, his ghost powers might manifest more strongly when singing. His music career obviously still means a lot to him, so he may be subconsciously boosting his influence on the land of the living in order to continue putting music out there.