I get number 1 all the time. It drives me nuts too. I play in a brass band and phrases from the music can go round and round in my head between rehearsals so much so that can end up hating a piece that I once loved. Words from songs do the same- they just randomly pop into my head I’m sure just to send me loopy.
Number 2- I read somewhere recently that our brains do the over active imagination/fantasy thing as it produces adrenaline and/or some other chemicals in our brains that we lack, and what better to force some adrenaline pumping than something scary (If I can find the link I will put it up). I don’t do the ghosts or spirits though, I imagine me being seriously injured/trapped by some accident. I’m a firm believer in positive thinking, your thoughts turn in to reality etc, so I have tried and tried to stop these thoughts by thinking of happy things, but it hasn’t worked so far, my fantasies just revert back to the bad thoughts again 
Johnah
REPORT ABUSE