Comes from an interview with Bono in Rolling Stone:
Then the plan is to do the Songs of Experience tour with the same staging?
Yeah, the Experience and Innocence tour. It'll invert a lot of things, but it's got the same basics. We've got some incredible staging ideas, but it's basically the same language as the last tour.
See above, looks like the I+E stage with some adaptations.
Arenas or stadiums?
Adam confirmed in June the tour will be indoors:
The Songs of Experience tour will be an indoor tour, as it "not something that would work outdoors".
Only one real rumour so far, and that is that U2 has been negotiating shows in the O2 Arena in London. Although most fans can fill out all the venues already when the continents will be clear.