I really can't add any other kudos for the magnificent job you did stopping to render aid and support until EMT's arrived.
I also will echo what several have said. It looks really cool to be rolling down the road in a tight formation but wow, is it ever dangerous! In addition to being staggered it's critical to allow LOTS of space between you and the bike you're following. You just never know what that bike ahead of you might be forced to do - swerve, brake, anything! The biggest danger here is usually complacency - you start off in perfect formation but close up tighter and tighter as the day goes on and you're feeling so good about yourself. I know I've been guilty of it and it's something I definitely intend to keep emphasizing to myself.