If you think you are a terrible teacher and have a hard time with beginners then don't become a teacher. It'll be better for you and your students.
I've taught for a year or two, I simply advertised myself on Internet for 20
You'd be surprised how many times I've heard "You play guitar?!? I want to learn", its like they were saying "Here, take me"
Sometimes but I'm ok with that. I sometimes need time off for recording. I only ever charge if someone has a really lame excuse for not coming. For me, that approach works best and parents love the flexibility.