Well, it's over. The urodynamics was not as free of "discomfort" as I had hoped. I am embarrassed to report that I "vocalized" something between a moan and a shout twice when the catheter passed through the prostate.
It took longer than I had expected. I was in the specialized chair with a urether up my penis for about 90 minutes.

Thankfully the nurse-technician was thoroughly professional and put me at ease.
The good news is that more useful results were produced than I thought might be the case.
It is likely (pending seeing my urologist) that I have urinary retention, over-active bladder, and my bladder does not sense that it should be telling my brain that I need to pee as early as it should.
Post-void, I retained about 13 ounces of urine. When I saw the amount in a beaker I was very much surprised. The nurse-technician said that I am borderline obstructed - in the grey area.
As for the cause? I may not know for sure. The nurse-technician said that, with as much pelvic nerve trauma as I have suffered, plus being bowel incontinent, that urinary incontinence is not unusual.
To my surprise, she sent me home not only with some pills to reduce the burning sensation in my penis, but with a handful of catheters, saying that I might need them to pee, following the procedure! She said that while she could not predict what my urologist would prescribe, with as much retention as I have, I need to self-cath and she thought that my urologist would prescribe the same. I see him in a week.
A question - for this level of retention, will a urologist prescribe cathing just once or twice a day? Obviously, I am wearing a diaper for the bowel incontinence and that makes it more complicated.
Thanks for everyone's support!!
--John