The captured image itself can have an exif orientation tag to describe how it should be rendered. Not all viewers support flipping though (our post capture viewer does not ). Videos will be a different story

It's related to what the camera sensor sees and how we render that to the screen. I can give you a more detailed explanation if you so desire

Android flips the viewfinder for front camera. I am not sure what iOS does.

I can do some tests and see. I am just a bit busy these days trying to get panorama functionality but still failing