On the SAT prep thing, the kids I mentioned earlier both took a prep course, and nevertheless got lower SATs than several other kids in their class who did not take a prep course (and who didn't get into Harvard).
Neither of them ever did anything other than minor community service. One had a summer job, but his father got it for him at his workplace. Neither of them ever took an independent study, or pursued a course of study outside that offered by the local high school. What they *did* was get straight As. (The kids who didn't get in also had A averages, but a few B plusses.)
This pretty much flies in the face of most of the reasons usually put forth why some kids get in and others don't. Must have been the essays.
BTW, it did occur to me to worry that colleges assumed that my kid achieved his SAT score as a result of taking a prep course (he didn't), and assumed that we could afford to send him to CTY for four years and so he was "privileged" (he got a scholarship, and the rest came out of our home equity). My kid had violin lessons, but I didn't go to the dentist for 10 years. (Luckily I have strong teeth and don't build up tartar.) But "I didn't take a prep course" and "I got a scholarship to CTY" aren't things that can be worked into an application. Or can they? Must have been the essays!