Noises

It's pretty hard (impossible) for me to interpret what a "crackling" noise is, as different noises sound different to different people.

Try to determine exactly what part of the engine it's coming from. Front, back, right, left. Also, tell me if it does this only while idling in park/nuetral or while driving as well.

The reason I ask for specifics is to eliminate guessing and/or confusion. In your reply you say "It does not happen at park/neutral UNLESS it hasn't warmed up". So that must mean it DOES happen while idling in park/neutral. Then you say "once its warmed up, the sound goes away for the rest of the drive". So does that mean it makes the sound while in park/neutral AND while driving? Keep in mind, if the car is hot or cold doesn't matter at this point. I'm trying to narrow this down in a logical order without having to make guesses that will lead to nowhere.

You'll first need to eliminate the simple things. Check the tightness of the belt as well as the condition. Usually this would cause a squeaking noise, but I've seen/heard stranger. If this isn't the source of your noise, remove the belt and turn all of your pulleys by hand. (Try to turn them fast) If one/more of them are hard to turn and/or make any noise, that'll be the problem.

If all pulleys check out good, purchase an automotive stethoscope and use it to listen to various spots around the engine. However, this'll mean removing parts of the engine once you've located the source if it turns out to be internal. If you need a specific procedure, let me know.