We use a doggie door and if our situation was any different I would be concerned about all those issues. Dognapping or other animals, but in our household it works out well. We live in the city a few floors up with a nice enclosed balcony. We have a little pee-pee and poop area for her. Don't worry we made sure there was no way she could jump or fall off.
Also we don't let her use the doggie door when we are not home. She is stuck using her potty pad (which I am a feeling she is not a fan off).