I'm a new GSD owner myself, and what has worked for us is we got her into a routine -- i.e. we woke up at the same time every morning to let her do her morning business. Right after that we fed her and let her out again. That way, she knew she had to go outside. For sake that she would alert us, we bought bells to hang on the door so that when she was near the door, she could ring them to let us know "hey, I gotta go!" and oddly enough... We didn't teach her how to use it! She just did it on her own.
For feeding, we feed her three times a day to spread out her intake as she liked to eat very, very quickly... to the point where she was just inhaling her food. She's eating normal and chewing her food now that she's growing mature. Spreading her meals helped out a lot.