1. You can manipulate your own gravity and whatever you touch. You can simulate enhanced strength and speed by altering the gravity of yourself to move faster, and make whatever you lift weigh almost nothing. Make objects crush themselves or blow themselves apart. You can move however you want on any way on any surface. Repel projectiles or attract them to alter their trajectory. And have a psudeo form of flight. But, the size limit for objects is a semi truck. When an object leaves your touch or field of affect (which is roughly 3 inches from your body) it returns to its normal gravity. Prolonged use is physically exhausting.
2. You can manipulate your surroundings gravity. You can move objects in a telekinetic like manner by manipulating the gravity around the object. You can crush or pin objects and people or make them light enough to simply float away. You can compress things by making gravity in the center of the object incredibly strong or rip itself apart by making the things repel itself. You can make barriers of highly condensed gravity to repel attacks. But, you cannot control yourself or the gravity near your body. If you don't change gravity back to normal, it will do so itself overtime. The area of effect is within your immediate vicinity (roughly 50 feet around you). The size limit is a large van. Prolonged use is physically exhausting.
You are not negatively affected by any alterations to gravity. No, your gravity isn't strong enough to affect time or create white/black holes. You can decrease the drawback of using your powers is physically exhausting by training. Ask questions if more info needed.