your information is not correct for Shanghai. Shanghai's policy is to allow all the kids below 10th grade to join local school regardless their hukou status. Beijin probably has more restrictive policy. For people not living in China, Shanghai is a city with population of 23 million. This is larger than population of a lot of countries. If Shanghai's system is good enough to get this kind of result, I think on state level, US should also be able to achieve better performance.
From local news, There are 6374 students from 155 school who took the test among population of over 90,000 15-year old.

I thumbed through the book but not impressed.
The author probably has used excel as best as any one can in doing the task he intends. But for most of people, the effort to acquire the skill by reading the book is not well-spent, since one can probably learn other tools which really intended for scientific analysis.

For statistic packages, R probably is much better, though I would prefer SAS. Try a huge data set (200MB, and put it in excel, your system will crawl before excel crashes, but in SAS, it will be really fast, and provide much more statistics. How much faith do you have in Excel's statistical function anyway?
I don't.

As for differential Equations, I would try matlab, if I really doing NA, I will choose netlib's packge anytime over Excel.

One can know Excel really well, and bend it to do all kinds of job, but in the end, it can only do that much. you probably can use bash to write a trading system, but why bother?