How often do you have to switch between night and day shifts?

When on duty, are you at the airport or do you just have to be staying near the airport to get there in time?

Also, for a King Air position, is there a minimum number of turboprop hours required? I have no turboprop experience, but have 3600 TT, 1200 jet and prior single pilot 135 twin cessna experience. Wondering if they'd consider me for the King Air. Haven't decided if I want to switch gears from the regional I'm at. But there's something appealing about EMS flying.

Thanks in advance