I get rid of all idiot light (after all I'm no idiot) I I'd put a neutral light in my last project but just because I needed something to fill the space left by the steering damper.
I generally just use turn signals on the back, I figure I'm watching in front of me, I know when I'm turning. But I can't control if someone rear ends me.
No horn for me, I don't use it In my cars so I don't need it on a bike.