I need help with creating a horror mod

I have never used this before but I have an ambitious project. I am creating a horror mod. I have already made the model, texture & animations, I just don't know how to mod. I have 4 things that I want it to do. First, I want it to observe the play from far away with three animations that would randomly occur, two of which would play sounds. It would stay there and stare for 1 minutes if the play does not look at it, then it disappears. If the player does look at it, it would either immediately disappear, or disappear if the play looks away. Secondly I would also like at random times for the mod to play a sound for the player to hear. Thirdly, I would like for the mob to follow the player from 5 blocks away. If the play were to look at it, it would disappear, this would have a low chance of happening. And lastly, after a really long while, during a stare with a specific animation, it would play a different animation, disappear, reappear 20 blocks from the player and starting chasing. If the mob gets  close enough, it will play an animation and cause damage. Does anyone know if there's a way for me to make this happen?