Well, it raydiates out. Just a lot of rays.
Well, that's really up to the DM, but more importantly, as I already pointed out, you're no longer in service to a higher cause, which means you'd be keeping that divine power to serve your own selfish desires. Divine power does not spring from one's own selfish desires, it comes from adherence to belief in a divine source. The source in this example would be the mission. Clerics of Heironeous don't get to keep casting spells if Heironeous kicks off, nor if they stop worshipping. What do you propose would make more sense than this?Also, pretty much, yeah, though losing divine power once the task is completed doesn't sound too fun to me.