How awesome that you and your friends want to get involved!  How about getting teams - since it's an overnight event, have a couple of parent be chaperones, but the teams be made up of all your friends.  It is, after all, like a slumber party!

See if your school will let you do fundraisers, like the class that raises the most money gets a pizza party or something.  Find out who the American Cancer Society staff partner is for your Relay and they can get all kinds of information for your school.  There is even a program where the students get a film canister and collect quarters. 

Just being active in Relay and getting your friends involved where they learn about Relay is wonderful.  I applaud you!!  If you want to help at the event - maybe you and your friends could help with the survivor dinner - or handing out whatever your Relay gives to the Survivors at the opening lap.

Good luck!