ParsingFancy exactly!! My BIL is a head of history at a secondary school. He got a good degree in history, which he is passionate about, then a PGCE, joined a school, and worked his way up.
He 'controls' his class because he is strict but also very bright and has a sarky sense of humour. He also reads around his subject constantly, keeping up to speed with current historiography. That academic knowledge is part of what makes him respected.
Starlight your post makes me despair. Teaching is not about making children do STUFF, LOTS OF STUFF which can be broken down into 'tasks'. It is about introducing ideas, debating skills, ways of thinking, and different approaches.
If you don't know what those different approaches are, if you haven't sat down and read through them thoroughly yourself, you can't teach them. You won't know them well enough.
Teaching is not about stuffing information from Wikipedia into children's heads.
And no, you cannot keep ahead of them through the textbook. Believe me. I teach (not children) and you will always, always have the smart alec who tests you on the first day by saying 'But I read X which contradicts what you just said'.
How do you deal with that? Making them do tasks? No. You deal with that by knowing the answer which makes them respect you. By being able to think on your feet in your own specialist subject.