Thanks all. Concert Window was/is great to work with. They even did a telephone call "soundcheck" with me at 4:30pm. Everything was working fine then, but apparently I needed to refresh my screen right before start time in order to get the mic back online. That accounts for the video-but-no-audio first minute or so of the broadcast. Once I refreshed and the computer recogniZed the mic input again, I had sound, but forgot to hit the "Broadcast Now" button again, so I played for a couple of minutes where everything looked fine on my end but all you could see was the curtain. Once I hit "Broadcast Now" again, everything was fine. There were people in several countries listening, but I only know that because I know the people involved. They do tell you how many people are listening and their names, but not their location. Internet upload speed was about 4.5 or 5.   

Did I have fun? There will be a learning curve for sure, at least for me. I was fairly distracted by a combination of concerns about the tech issues and a scrolling screen of people's comments which went by too fast for me to see. And yes, I did have fun. I think it has real promise.