...I have one drill that has a 1/2 chuck and it quit on me a few weeks ago. How hard is it to switch the chuck?
That greatly depends on the drill. There's a set screw of sorts in the bottom of the open jaws that must be removed first. That set screw is LEFT HAND THREADED! (That's righty loosey, lefty tighty LOL). After that is removed, the chuck should unscrew with regular right hand threads.