Lets say I have a{SpellheartChimera} and an {Runechanter's Pike} equipped to {Niv-Mizzet, Dracogenius} and I want to re-attach it to the Chimera, can I just repay equip and equip to chimera, without anything dying, being cast, or anything?
Yes you just pay the equip cost. There's no reason in the given instance that you would have to do anything other than pay the equip cost.
So if it's already on a creature you can just Willie-nilly equip it to something else?
You betcha, so long as a) the creature can be targeted, b) you have a way of attaching it, this generally being the equip cost, c) you control the creature you are attempting to equip to and d) you are equipping when the stack is empty, in other words, at sorcery speed
Really? Huh, I didn't know that. Thanks!