http://en.wikipedia.org/wiki/DiMeo_Crime_Family
This page is the "hierarchy" of all the known NJ crews. It appears as though Christopher was promoted to Capo of Paulie's crew when Paulie was made Underboss to Tony. So Paulie is #2. And as has been mentioned before, Paulie will NOT be a rat. As far as Tony/Junior goes, remember long ago when Junior was arrested, they ended an episode at the FBI corkboard by removing Junior's picture from the top of the chart and moving Tony up, scratching off "Capo" from the sticky and writing "Boss". This pretty much signified that Junior was out and Tony was in.
AJ: Interesting to note that he now further resembles Tony when he was growing up. Some of you may recall in the flashbacks Tony had about his youth, he looked very similar to AJ when he was in his teens, and when he was a little older, he had long hair. I think they will eventually try and have AJ's arc mirror Tony's but because AJ is such a dips**t, he'll screw it up somehow.
Meadow: Wouldn't surprise me at all to see her get involved. And naked.