A lot of these rumors are stemming from an english speaking production crew member (not on GNR's team or payroll...) who is apparently a mega GNR fan and got to see the soundcheck today. He said Street of Dreams, as well as others, and Meegan's story confirmed that. Not sure where the Breakdown background rumor is coming from, but fuck it, it's exciting to think about.
I personally believe it. If they got their asses out there a whole day before the show, and probably plan to again tomorrow, I think they probably played a shit ton of stuff they haven't gotten together and played in awhile.