Thanks a bunch for this, very helpful stuff. And congrats on your well-earned success!
I just launched an app a couple of weeks ago and am past that first spike on your graph (we were reviewed on AppAdvice last week and on TheNextWeb yesterday).
So following your formula for success, I need to add some iOS 5 features and get Apple to feature it. I'll get on that right away. ;) It seems like every single success story of app devs has that in common: they were featured by Apple. That's the maddeningly frustrating part of it all because that process is such a black box.