I went as well - i don't have much to add and my questions were certainly not as insightful as yours - but i will add that i was told that six balloons had launched, and the real balloons are larger than the demonstration as it's pushed down to fit into the demonstration hall. They didn't have a demonstration of the building antennas.

Multiple balloons in the air form a mesh network, allowing you to put your uplink only where it's convenient for you - which i guess is the key to making this a viable solution somewhere inbetween 3G towers and satellite internet.

It was a fun event, i hadn't been to the airforce museum before - lots of kids with helium balloons, poster giveaways and folded balloon animals. Someone was wearing the first Google Glass i've seen and lending it to people to try (that must get old pretty quickly).