I agree, that's fast. When I was younger, I'd go through 3 novels a day - got one before school, and read mostly during passing periods, then one at lunch for the afternoon passing periods, then one after school for the bus ride home. Maybe 100 pages in 30 minutes, for light reading? The G&T program brought in someone to "teach" us speedreading, and the "10 times faster than average reading speed" demonstration was slower than my normal reading speed, but not hugely slower.
I tend to want to stretch books out now, so try to read slower. I find myself intentionally flipping back to slowly re-read pages that I automatically skimmed through without paying much attention - but without missing out on anything important. So I'm not sure that "can answer specific questions" requires the reading-every-word type of "thoroughly," at least in my own experience.
I was a good writer, and would also be concerned about a kid who seemed unable to organize his writing. Uninterested in organizing wouldn't necessarily concern me - it's hard to get your thoughts out fast enough to keep up with your brain, and organizing as you write makes it even worse. (My solution was to let everything float around in my brain until it organized itself. The organizational methods they taught in school worked so poorly with how I thought that it was easier to write the paper, then create the outline / notecards / whatever intermediate steps the teacher thought I should need.)
