I have ordered new power slot rotors and hawk ceramic pads. My question is do I NEED to replace the pad sensor before putting these in?

You don't have to if youre careful not to damage them.

how can i tell if the sensor is damaged? besides the obvious physical damage...

It'll throw an error message in the cabin of the car. If somethings wrong... it'll let you know ;)

just replace them, they are cheap, better doing when your already in there, but no you dont NEED to

thanks for the advice guys. i think i'll just replace them...

Wouldn't hurt, its cheap