advice for Executive Disorder/ADHD in a formal meeting?

I'm a PhD candidate closing in on my defense and I'm panicking again because I remember my preliminary defense, after which all the panic attacks started, and during which I began to realize my thought processes are for lack of a better term retarded.

I have already been diag. with generalized anxiety disorder and dysthymia since childhood. Recently a friend whose family member was diag. with Executive Disorder recognized some of my symptoms as either being high-functioning ADHD or ED.

In a nutshell, I am a highly visual person and can understand, interpret, and retain written words much better than spoken. Visual instructions/info are the key to my understanding, even BETTER for me is DOING the thing in order to learn it. I cannot follow and even less so retain spoken instructions (think directions given to a location - with five different turns and other descriptions - doesn't work for me at all, never has).
What makes this actually bad is that while I can take notes, I then miss what is spoken. I cannot concentrate on spoken sentences/meanings of sentences while writing another - just like I cannot follow a TV show while someone is talking to me.

So what this mean is when I go into a PhD defense, I will be asked questions, expected to answer, and then there are discussions. This would all be fine for me should it be done on paper, but it's not, it's in real time, and I have delayed brain synapses when it comes to processing questions, particularly convoluted or multi-faceted ones!

I realize finding another person in my exact situation will be difficult, but I suppose there are parallels to my situation in other professional walks of life.

1) I don't know if I should inform someone about this problem. I'm high-functioning, unmedicated as it is (aside from recent/occasional clonazepam), and have lived this way for 30 years. Most people dismiss it as an excuse for special treatment. I MIGHT have time when I go back to campus to meet with a counselor and perhaps get evaluated quickly, and my uni is officially VERY adamant that mental or physical illness be accommodated. My committee chairperson is an understanding person, but is also a "just pull up your bootstraps" person.

2) If I'm not awarded any sort of accommodation whether I disclose or not, what can I do to make my experience easier? Attempt to write down all that is said no matter what? Simply ask people to repeat themselves? Ask for a moment to contemplate? Certainly those are not at all unusual, but I may need more than 30 seconds to think about something. That's how it was before, with me...

3) Will disclosure make my committee (de facto judges) think less of me? "She's not fit to pass"? "She wants special treatment because she's lazy"? Will me seeking accommodation harm me in any way?

Thanks to anyone who has any advice.