I'll agree that you need to learn a lot more about dogs before you get one, but be careful of what you read and believe from websites. Some of them are written by people who think they know tons about dogs in general because they've grown up with them their entire lives or maybe their MIL breeds them or they worked in a pet shop for three weeks. Your best dog care info is going to some from vet based websites, preferably organizations that support a large diverse group of vet rather than a single vet clinic. Those sites have to make sure their info is based on current research and not just current popular opinion, otherwise they'll hear about it from the vets correcting them!!! Another good rule of thumb is to weigh confliciting advice, which side is supported more and who's doing the supporting.
Having said that, dogs are geaneralists in terms of nutrition, they can eat a wide varieties of food and still be healthy. There's nothing specifically in meat that they require. Animal based proteins do have a different amino acid ratios than plants and the tend to have higher amounts of essential ones, but, just like with humans, the right mixture of plant proteins will provide adequate amino acids amounts. Being more generalists, dogs have a better ability to detoxify plant toxins than cats, but not as good as humans and so might accumulate more damage from the toxins than a human on the same diet.
So, you could have a healthy vegetarian dog, now the question is:do you want to cook for your dog or do you want prepackaged? Homemade diets need to be watched carefully to avoid nutritional defiencies and excesses, they are also time consuming to prepare. Commercial diets should already be complete and balanced, and therefore require less work, but may also contain stuff you don't want to feed your pet, like preservatives and compounds to balance the diet. I've seen a few veg dogs and some are super healthy and others not so healthy. In short, how they do, depends on the dog.
As far as GSD's do, they require more dedication to train. They are bred to be intelligent and dominant. This translates to a dog that gets bored easily and may try to spice things up on their own by inventing new games or getting into trouble. Some of them tend to be fearful and are more likely to be fear biters if not trained properly. GSD's also have lots of health problems, not just hip dysplasia, but also djd, spinal cord demyelinatation (degeneration of spinal cord causing paralysis), bloat, and others. I've seen too many who have problems with allergies. The thing with water in the ears is far fetched. They can get ear infections from frequent/persisitant water in the ears, but they won't die from it (unless you let it get really, really bad and even then...). If you really want a GSD, I would recommend actually getting a mix of one, they're much healthier in general.