So in such scenario, is it safer to wait behind the bus so that the turning car driver can see me? (3 possible positions of bike)
Yes. I would stay behind the bus, in a position where you can be seen by both the driver of the bus in his/her left side mirror, as well as being visible to the driver who is turning left. As soon as you're past the intersection, then you are free to return to the right portion of the lane, unless of course the bus is stopping.