All of my comments hinge on one major component: how much the dog has been trained. Below, I am assuming a dog that has been intentionally trained on how to behave (if you don't teach them, they don't know).
So my question for all of you is,
what is it like to own a CONFIDENT Shepherd?
Like having any well-behaved dog plus a little more. When GSDs get into the groove and they're confident that they (and you) can handle whatever comes at them, it becomes almost like a partnership. They act with dignity, tranquility, and know just what to do (because you've told them). It takes a few years before puppies get to that point, though.
Can they be walked in public without showing aggression..
Of course. Jack gets to come with us to the market, on trails, dog-friendly stores/bars/restaurants. He likes going and watching the people, and he usually gets heavily rewarded for his good behavior (dog treats, bird feet, pieces of yummy meats like bacon, or in the case of trails, off-leash time.
Can they be near strangers without the need for aggression?
Yes, provided there is no logical reason for them to display aggression. Like someone threatening you or acting strange towards you.
Jack has no problem with being around strangers, though he's hesitant about strangers petting him. He'll usually duck away when someone reaches over his head and if they persist, he barks at the person (we correct this, and he's getting better, but I think that's also an understandable response--we allow one bark and then he has to sit and be quiet). But we just ask folks to let him sniff them first, and then he's good to go and will accept petting very happily.
However, if there's a small child that absolutely loves him, he'll be the friendliest, most playful, and gentle dog. No reservations. He loves my neighbor's 3-year-old, and treats her gently while doing everything in his power to keep her giggling and clapping.
Do they make good dogs for someone who wants to bring their dog everywhere?
Yes. GSDs, when well trained, are some of the BEST dogs to take everywhere. Primarily because they're so handler-focused and are more interested in what you're doing vs everyone else.
Do they ever show aggression towards their handler, or other dogs?
Unprovoked? No. Provoked? Yes, if they can't avoid confrontation first.
Jack prefers to avoid conflict where possible, but I've seen him unafraid of pushing back against another dog that's being a bully to him.
He's also gotten very annoyed with us on occasion (like clipping his back nails). It's always our fault for putting him in that kind of position an not listening to his warnings or telling him what to do first. Accidents happen, and we both back up and take a breather before trying the thing again later (if it was something we need to do). There's never any ill will afterwards.
And when I mean the above, I don't mean a serious attack. Just growling in protest or trying to wrestle out of the way. He's snapped a couple of times, but always with perfect restraint. Never anything more than teeth touching the skin (or neck in the case of a dog). That restraint had to be taught when he was very small--exactly how much pressure to ever apply to human skin.
Now, there is something he does that LOOKS like aggression, but is pure overexcitement. Whenever he runs outside and gets very hyper, he'll sometimes grab our ankles or arm, and chomp a little too hard.
Another one being, were you a first time dog owner when you got your Shepherd? Or experienced, and what do you believe this breed is mostly directed for?
Not a first time dog owner, but a first time GSD owner. Which might as well mean I'm a first time dog owner. XD
Shepherds need a job, somewhere, somehow, sometime. They are bred to WANT to work. They love working, especially when they understand the tasks and the rules of engagement. Work can mean anything that involves focus, training, and physical execution of some kind of task.
And this falls into all other realms of their lives. They're a breed that thrives on rules. They like rules, and they like knowing the rules. This makes them happy, obedient, and confident. I think this is why you've probably read that GSDs need a "firm" handler. By firm, they mean that you're willing to establish rules and keep to those rules. I've learned you really can't pussyfoot around with these dogs. You can't let them just get away with bad behavior. They seriously need good leadership or they'll start making decisions of their own accord. They aren't like a lab that will automatically default to your will. Shepherds only default to your will if you prove that you're worth listening to. That really doesn't take much, and it doesn't take heavy-handed treatment; it just requires clarity and consistency.
But then, I've got nothing on the people on this forum who've owned GSDs all their lives... They know even better than I.