Hi Rachel,
If your neighbor takes the Rottie to obediance training, the dog will learn. The old saying "Old dogs can't learn new tricks" is just a myth :) But the dog has to be properly taught and the training reinforced. Yelling at the dog will not help at all. It will just make it stressed and confused :(
Rotties are NOT naturally brutal or mean dogs. The breed can be just as loving as any other dog. Harsh treatment and neglect will make the dog just as "bad" as say a poodle. Unfortunately, because of its size, when bites do happen, it will be worse than the poodle :(
If it's possible, ask your neighbor to introduce you to the dog with her present. Ask her if it has any fears of being hit or yelled at. Then always be kind to it. If it knows you, it can become your friend. My dogs adore my next door neighbor's teenage son. They cry in happiness when they see him. It's quite embarassing sometimes :) :)
Please discourage any friends of yours from teasing a dog through a fence. Screaming, throwing items, and growling at strange or even friendly dogs is mean and a dangerous habit :(
Don't run.--- Walk up to people who have dogs. Dogs have different vision than people do. Running around makes you look as if you are prey or a threat.
If there is a loose dog on the street, stand quietly and look down at the ground. If you have younger children with you, try to make them do the same. Just be a tree :)
I hope your neighbor has a secure yard for the dog. If it is just tied out on a line, then there can be problems. If she doesn't fence the dog in properly and there is trouble, then she will probably be blamed for it. I hope she's a good owner and things work out ok for all of you :)
good luck,
Sara