Chengdu in October 2012!

Good evening! Im from Portugal and im travelling to Chengdu in October, and theres some (a lot) of questions i'd like to ask, but the main one is, Which is the best way to go from Chengdu to Shanghai? Is there any High speed train in Chongqing to Shanghai, so i could make the connection by train? Its very expensive?
One more question: Its cheaper to buy domestic flights being in China already, or its the same price as buying from Portugal?
Thank you so much