2000 Ford Explorer car questions

First, does the sound seem to come from the engine? Does it make the noise when the car idles? If so, try this test. With the engine running, open the hood (make sure to keep yourself away from moving parts, especially the fan) take a small amount of water and pour it on the belt to see if the sound changes. Protect your eyes and wear old clothes because the water will spit back at you. Let me know what you find.

As far as the vehicle only starting in neutral and not park, there is a switch called a neutral safety switch. Its purpose is to only allow the engine to be started when in park or neutral and not in drive or rev. When they go bad, they do exactly what you have described, only start in neutral. That will most likely need replaced.

Let me know what you find.

Joe