Are they allowed to have their KERS charged for the start?
KERS can't be charged whilst the car is stationary during a race pit stop. However, as far as I'm aware, the regulations don't actually mention anything about in the garage. And even if that's not permissable, the amount of braking that goes on during the parade lap should give them a good amount of charge anyway.
If the rules don't say anything about KERS being charged in the garage, that could be pretty big omission, depending upon how quickly it takes to charge up the KERS. It could be that the drivers could charge up their KERS on the parade lap without too much bother.

Ayrton Senna: WDC 1988,
1989, 1990, 1991
McLaren: WCC 1974, 1984, 1985, 1988, 1989, 1990, 1991, 1998,
1999, 2007McLaren: WDC 1974, 1976, 1984, 1985, 1986, 1988, 1989, 1990, 1991, 1998, 1999, 2008