Critical Mass uses ad hoc organization through the ride. Every cyclists looks out for each other. It's important for safety that all the bicyclists stay together in one large group. Safety in numbers.
Stop and "cork" open intersections to cars. This is a very rewarding experience and a good opportunity to see the beautiful parade go by. After corking you'll be at the back of the ride, and can play the peloton game of racing to the front.
People at the front need to choose the route in real-time and shouldn't get too far ahead. The group will stop after the top of bridges or big hills and let everyone catch up. If the mass is big it should stay on larger streets so we have more lanes and can ride together.
Vancouver Transit Camp is an open-invitation unconference about transportation being held on December 8th. The BC government has shown an appalling lack of wisdom in handling transportation planning. I'm hopeful that the geeks of Vancouver can start improving things despite them. Check the website for some funky transit inspired designs, sign-up info, and more.