The only remaining 2013 release with the potential to move the needle in a disappointingly light late-2013 releases schedule are the third album from Columbia’s One Direction, hitting on Monday of Thanksgiving week (11/25), with estimates currently in the 500k range, and RCA’s Britney Spears, though her very light promo schedule, with little or no TV around the release, could put the album on the low end of the 150-200k forecast.
Actually, the week after Thanksgiving usually give albums bigger drops than usual, so One Direction will lose at least 75% 2nd week, it's all gonna depend on how large their debut will be.
She can perform anywhere outside the US, but in the US she is contractually obligated to only perform in Vegas (but merely concert type performances, stuff like award shows and the like are allowed). Celine has the same contract, and she performs overseas and on domestic TV without interference. Robin Leach confirmed this.
Now Britney actually wanting to is a whole different story