Get Your Dog Care Questions Answered by Experts
It can be true but it doesn't have to be. I suggest that, if you truly want to form a relationship with the dog, you start an obedience class with him right away before the behaviors get worse. He needs to realize that you are the alpha and not him. This is the best way to do it.
There are small things that you can do as well. Be sure that you make him sit or "work" for treats, don't pet him until he is calm and it's on your terms and don't let him tell you who's boss!
Let me know if you have more questions.
Neutering the boys usually does not cause a tremendous amount of pain. He should be up and moving around the next day, probably the same day. It will help to ease some of the aggression but not all of it. The rest is up to you. You have to build a relationship with him in which he knows that you are stronger and more important than he is. Obedience classes are the best way to do this.
Let me know if you still have questions.