The problem with purchasing a horn (unless you go with a cheap or used one) is you will play on whatever brand the corps you go to uses in the end. You will end up with a horn sitting in your closet most likely, so don't spend a bunch of money on a mellophone is my advice.
What is being left off of this is that at the very end he mentioned that DCI had committed itself to protecting the members and this MM then questioned why DCI allowed the Orlando event to start back at the time it did with lightning still within it's 15 mile boundary. I think that is what really irked DCI more than just reading the GH thing was questioning them about that Orlando situation.
I believe most rehearsals are open to spectators, but be respectful and don't cause distractions. Also, staff may ask you not to take video of what they are doing, so be prepared for that too.
Crazy that they hired the law firm already representing the board to investigate. That would not be an independent investigation - it is no wonder they didn't cooperate.
A member of my contra section in '96 marched and he was in the Naval Academy at the time (it was the year after his plebe summer). Not sure how exactly he worked that out, but he did.