With respect, this is kind of like trying to use the lack of a bit and bridle to dismiss the overall concept of a horse.
Those issues are things that we in the field would call "engineering details". If you can get it to work at all, these are not apt to be massive problems. Steering, for example, is almost trivial. Assume, for a moment, that you have the exotic matter required to form a warp bubble. Steering comes from small alterations in the distribution of that exotic matter, to slightly change the shape of the bubble. Compared to the immensity of the base assumption, mere steering is child's play.
As for Hawking radiation - dude, you're talking about having a warp drive. A main deflector dish isn't far behind