You are required to yield to vehicles in any lane of the circle, as you explicitly acknowledge. If you do that, then turn signals are irrelevant. If people do

You are required to yield to vehicles in any lane of the circle, as you explicitly acknowledge. If you do that, then turn signals are irrelevant. If people do use their turn signals, it's ambiguous, and only applies for a split second, as you also explicitly describe so it only encourages accidents. Therefore don't use your signals, don't guess what people are going to do, just wait for the car to pass. Do you also turn left into the same street as someone turning right? I don't have chapter and verse citation on whether that is permissible, but I've always thought the person turning left is supposed to yield even if there are two lanes and nobody is oncoming from the POV of the person turning left.