Eerie Things Started Happening to Me

Hello, I am 25 years old and just wanted to ask you people some stuff. Here are three small stories each briefly describing an incident.

1.) Spring 2002: There were loud bangs from out of nowhere in my house. My dresser banged loudly once while I was laying in my room at 2-3 A.M. It was as if someone kicked it full force. The whole night, and many nights prior, I heard feet scraping around on my carpet. It was creepy. I also heard someone dance down my hallway once. It definitely was not other occupants in the house. In 2003, I also heard a very loud bang when I was sitting in the basement late at night. I immediately flew up the steps to the room it came from to find nothing. Nobody in my house heard it when I asked the next day - they were asleep. These bangs were VERY loud as if someone dropped a desk chair from 3 feet up.

2.) Summer 2000: I saw a human shape walk up to me in my peripheral vision, but when I turned to look, nothing was there. It literally vanished after being right next to me. That same night, the fan started spinning (the wrong way) on its own.

3.) Summer 2004: I always heard of that "feeling a presence" myth, but I never actually felt one. I never understood it until I actually felt it one night. I was sitting in the basement on the computer. When this obtrusively invading thought interrupted my mathematically preoccupied mind (I was programming the computer), and I suddenly just "knew" that someone was there and that it was watching me. When I looked, nothing was there, but I could point out exactly where it was. This sudden thought wasn't a result of a wandering mind - I was busy doing something irrelevant. This thought literally, obtrusively injected itself into my consciousness - just like when someone interrupts you. This was right after my grandmother died so it might have been her.

I'm having trouble conceiving this 'ghost' thing because I always understood matter and the universe in terms of physics (science). I remember one night when I was in high school, my friends and I went walking through a grave yard drunk. I urinated on someone's tombstone just to be a smart a**. Might this have something to do with it? I was stupid at the time and am sincerely sorry for doing that disrespectful act to someone's tomb.