Someone help! Do I have ghosts in my home or following me?

That little ball of light would be called an Orb. And with the banging of the seat? No explanation for that. But going back to the orb try to recreate the event. Is there a road at the end of the mountain? Maybe helicopter? Airplane? Think of what could have caused that event. But if nothing fits then you may have a spirit w. you. But don't worry, if it doesn't harm you then don't over react.