I'm not an expert by any means, not a breeder or trainer, but I have owned German Shepherds my whole adult life and let me tell you, I wouldn't own another breed.
Your 1st question, yes a german shepherd can fit the description of what you want in a protective reliable family member. Some of the "sketchy" behavior you are concerned about can be genetic or training (lack of) based on the dog. German Shepherds do require a lot of training to be happy, a lot of activity to be happy. A bored dog, or one without a clear set of rules to live by will make up their own, and more than likely you won't like them. (the rules they make that is)
Your 2nd question about breeders, how long has it been since you have contacted them? People get busy. I get busy and neglect returning phone calls etc, I'm sure you do too at times. Give them the opportunity to get back with you, or drop them another line. Good breeders aren't in it for the money, so it's not like a business for them. You can't look at it like, if they want my business they will do x y z.
Then about rescue shepherds, I don't have personal experience with this. Surely someone will chime in with their experiences. There are lots of threads that I have read though about rescues that are positive. The way I understand it is that the dogs and potential adoptees are matched. You tell the rescue what you are looking for, your life style etc, and they match you up with dogs they have in their system that might be suitable.
Good luck with your search!