And what percentage of the above would actually prepare a student to thrive at any STEM subject at, say, MIT, as an incoming freshman?

Unknown.  I think background in rocketry and motor repair is already what goes on applications for admission to such places i.e. a well rounded skill set is considered a good hand.  Say your rocket group got a projectile all the way to 50% less atmosphere and was able to aim and gain exposures of tiny astronomical objects while in flight.  That's what the big boy and girl astronomers do today with their modified 747.  I think an HR person checking a resume would necessarily draw a frowny face.

Yikes, my mistake:  I think an HR person checking a resume would NOT necessarily draw a frowny face.

Or maybe I'm wrong.  The establishment seems anti-rocket thse days.

I joined a little rocket club, multi-generational, everyone had a blast, but then the word came down, we were told from Homeland Security, that these Public Parks and Recreation Areas were closed off to rocketeers.  Was this connected to the post-911 crack down?  I think it was.  

And yet it's the military-minded North Americans who use rockets so much (e.g. cruise missiles), inherited German tech some of it (V2), not the Saudis so much, unless you count those Stinger missiles -- so you'd think HS would be more encouraging or rocketry in public spaces?  Where's their patriotism? 

Most schoolyards are too small and are in congested areas.  Some parks should be designated as friendly to rocketeers.  Ours came down with a parachute for the payload.  The boosters were light weight and totally tubular and not able to cause serious injury.