I just got an email that Google plans on incorporating their +1's into Adsense next month to help determine relevance of an ad: It looks like they are planning on incorporating +1's into all of their systems. Might as well get used to using them now!
Yes, I think so. They are trying to make Google+ available every where they are already present right now.
yeah, I also got their mail yesterday, I think they want people to tell whats interesting in ads. so that they will review the positions again, also for good adsense links because not only they will get traffic but also good SE position