Not normal but hey were all crazy here
At your age, definitely. That's literally all I could think about back then. It'll die down when you get older. Just don't act on your thoughts and you'll be golden.
No not at your age nor into your 20s. It's a good thing to think about so long as it remains "thinking"
Yes it is
Its ok but dont let it affect ur studies
Idk.... but i do. It's really annoying.