OF course, the spread is a cost and will always be there no matter what strategy or what method you use - most liquid markets are only one spread, but whatever it is, it should easily be absorbed anyway.
It will happen, but not often that the market moves in your favour by exactly 11 points, or exactly 9 points against you, but I would guess that at least 95% of my winning trades runs on from where I close and run on from where I'm stopped by at least 2 points, if not a lot more.
A coin toss entry is a ridiculous idea any way - if the market in question is going in a clear identifiable direction, why toss a coin. It seems a lazy gamblers sort of strategy to me.