When you say "flatten", do you mean to combine all these elements into one image? You can do that in Acrobat (File>Export To>Image>...). If you then import this image back into Acrobat, you will have an image-only PDF file. This can still be "lifted", so that may not be the right approach.
In general, where there is enough criminal energy, you cannot prevent somebody from taking elements out of your PDF file and repurposing them. You can just make it harder. I would use the approach of protecting the PDF file from content extraction via security settings. You can still add form fields on top of such a protected file, and have them be editable. But again, if somebody wants to break into such a file, it's not impossible (and after spending some time with Google, you will probably find out that it's fairly easy).
And yes, form fields can be rotated. Just bring up the field's properties, go to the "General" tab and change the rotation:
Karl Heinz Kremer
PDF Acrobatics Without a Net
PDF Software Development, Training and More...
http://www.khkonsulting.com