Hannan likely got picked because of all those great one-on-one battles he had in the playoffs against all those top forwards. Bouwmeester was likely a close second with his great skating abilities and his solid performances at the last two World Championships, but he brings less of an edge that Hannan does. Souray's end of the season was anything but memorable, his playoffs were not very good, and he never regained that form that we all saw and admired for the first half of the season. Given that, I don't think he was ever in the running for this spot.
Will they play on the internationnal ice surface size or nhl size?
Who will replace Blake on the PP?
I don't know the answer to the second question, but for the first, they play on NHL size, because they won't destroy the arena's for this tournement, the players will just have to adapt (if they don't play in North America)