Posted 30 November 2011 - 10:55 PM
Regarding browser usage, the w3schools.com data is not reliable because it isn't representative of the web. Here's the quote from that page:
W3Schools is a website for people with an interest for web technologies. These people are more interested in using alternative browsers than the average user. The average user tends to the browser that comes preinstalled with their computer, and do not seek out other browser alternatives.
In general the numbers for w3schools for Firefox and Chrome will be much higher than the rest of the web, something like 15-20% higher.
The best way to determine what browsers to design for is by using the analytics from your own site, that way you know what your customers are using.