I'm a Master Prestiger, so will double XP weekend affect me? Since only the in game score affects my rank on the leaderboard.
If you care about overall leader boards then yes it will. You still get score added and it helps you to get higher up on the leader boards. Plus it's also helps boost the population and makes the game fun!
They will probably have a stream again and you can try to join games with the developers. Pretty sweet.
P.s if they do decide to add more ranks like mw3 did any extra xp you get after you are max prestige will be added towards the new ranks IF they do add more. So if your max prestige for 2 months before they add more ranks. All the xp you get in those 2 months get added towards the new ranks.. So you never could be helpful.