Since you invited feedback, here's what my impression is:

1) You might be holding yourself to an unreasonably high standard if an A- is so unacceptable to you, that being unable to get it changed and unable to get the professor's reasoning throws you so off-balance. If such a minor thing escalates you to this point, then what will happen when you are faced with dramatically unfair things? It WILL happen. It's life.

2) The intensity with which you pursued getting the grade changed and getting him to explain why it was an A- instead of an A may have made you appear "unprofessional."

3) In my experience, many professors are extremely reluctant to hand out A's. It certainly varies from one professor to another. I've had some that never, ever gave out A's and were quite proud of that. To get an A- and be this unhappy about it is not going to seem reasonable to most people.

4) In the email volley, to me the professor was very reasonable, and was complimentary of your work. As your professor, he is entitled to judge your work as he sees fit. And when it comes to judging written work, there is no black and white to it. It's not a yes/no or multiple choice answer. Most importantly, how a professor judges your papers will be influenced by his overall impressions of you. There is no getting around that reality. In light of that, complaining about such minor things to the point that you tell academic staff that the professor is an *****-hole is going to affect you not only in that class, but others to come. Word gets around, and it may take a long period of serious demonstrations of respect for professors overall in order to counteract the effect of being known among professors as the student who reacted that way to an A-.

If it were me, I would talk to the advisor and apologize. I would humbly face whatever happens with the disciplinary thing. And I would do whatever I had to in order to adapt the way I react to things so that I don't go over the top.