1.no different, gtx 770 well perform like 680 and the 7970 GE is slightly faster than the 680
also there well be probably price drop for amd 7970 GE due to new nvidia GPUs
2.I don't know much about cooling, so wait until some one else answer this.
3.Where is it? o.O
4.Sorry cant answer this too, still a noob but all what i know is thier both are built on 28nm technology, u can say that the 770 is 680 but with other name[correct me if wrong guys still noob^^]
5.this is the best Solution as the 9970 will be 22nm technology try this :-AMD Radeon HD 9970 Specifications Speculations
6.I don't really know but u may find some info in the article above