a)  My DD's reading progress has been much more up & down than your DD's.  She began reading at 2, but didn't progress to sounding out unfamiliar words until about the time she turned 3.  Then, she went up a grade level about every two months until she hit 4th grade (about the time she turned 3 1/2).  That was pretty shocking.  

  She's a big reader, but still not into chapter books--the interest just isn't there.  I say that her progress has slowed, but the truth is that it's not her ability that now limits her; I'm sure she can decode on at least a 6th grade level.  So...my answer would be who knows?  But really, once a child is a fluent reader, education becomes much more about content than about the actual reading.  I wouldn't expect hugely-above-level reading ability to _necessarily_ translate into a need for hugely-above-level curriculum.