2) Look at this image to see the difference between different brands and their size 8 measurements.
http://www.nytimes.com/imagepages/2011/04/24/business/201104... via http://thesocietypages.org/graphicsociology/tag/womens-size-...
There's many variables to sizing. It wouldn't be impossible to create a database of measurements for every single piece of clothing.
And then there's the issue of shrinkage.