How do Pucci's stands work?

So Pucci has three stands. White snake, C moon and MIH. I understand that C moon is a gravity manipulation stand, but what about White snake and MIH.

What power does white snake have, furthermore I understand that somehow Pucci previous stand merged with C moon to make MIH, and he became the center of gravity. But how does that make him speed time and not effect living beings.