What should I do at, and what should I know about, bike shows?
Ok. It's basically a trade show and exhibition. According to your link it appears to be typical of trade shows/exhibitions. 

1. What should I do? Walk around. Explore. Watch events. Shop for products of interest. Ogle bikes and collect brochures. And also, talk with manufacturers about things you find of interest. 

2. What should I know about? It's not a test, so you probably don't need to know anything in particular. You might "know" about products that you're considering, but other than that...

Otherwise, you'll get to see new bikes, new bicycling technologies, and new accessories. And, it appears that you'll get to watch some bmx and mtn bike events.

Last thing... Bring along a friend who is vacillating about taking up bicycling. There's nothing like pretty gizmos to get someone started. ;~) And things like this are usually way more fun when you have a friend along.