I'm not sure, but I don't think you need to do those things immediately in order to get a Gates invitation. I think those of us who heard neither rejection nor offer of interview are on an "interview waitlist" of sorts (that will likely turn to rejection in January, but hey, there's a chance). Which college did you hear from?
Has anyone heard back from Arts or Physical Sciences? At this point I'm expecting to have to shoot for a different scholarship, but I guess it's not over until they send a rejection.