There are plenty of people who have GSDs as service dogs. They're very well suited to the task when the right temperament is matched for the job.
Yes, you can find a plush coat but as far as the dog, focus more on temperament. You can let the breeder know your coat preference but a good breed, as the one Jane recommended, is going to focus on temperament above all else. Be open and honest with the breeder you choose as to your experience and needs. Chances are they'll help you either find an adult dog to work with training or they'll have an older puppy they think will work for your needs.
Far as prey drive, each dog is different. My female has zero prey drive. None. My male is about medium. As far as training, again, each dog is different. Most are incredibly easy to train. Just have to find what drives them *food, toys, praise, etc*.
This is a breed that is meant to work. They like to work. They need and enjoy having a job to do.