Thank you for your post, but I'm unable to reproduce the problem using an iPhone 4S. I take a picture from my phone, store it in the Photos app, launch FileMaker Go, open a file with a Container field, tap the Container field, tap "Choose From Library", and select the photo just taken. In a new record, I tapped the Container field, tapped "Take Photo", and snapped a similar picture. Both pictures appeared the same without any flipping or stretching.
Let me know what I'm doing differently than you (or your client), and I'll try to replicate the problem here.
Does the orientation depend upon how the phone is held to take the picture, there are four orientations. On a film camera the images can be inverted and if you turn a movie camera upside down, the viewers will see the images upside down. I ask because I don't know.
The stretching is one option of the container field when you create it. Check your settings in the Inspector. You can alter the image inside the container by a container setting and you can also anchor the container to both sides of the window which would stretch it.