How do you enable Lightroom to auto rotate batches of images using each images content, not exif tag information?
I don't think you can. The auto rotate function is built into the camera. And I'm not aware of any such feature in Lightroom.
That is not possible.
To base it on the content is to require knowledge about the content, which is never known.
In the current CC version 2015.7 there is the option to individually have each photo analyzed and straightened based on the computer's best guess.