in the 2004 movie, why does Erik have a mini model of the stage and little 玩偶 and stuff?? cause if 你 ask me that's just kinda creepy...(especially when he starts switching their heads around)

Well, he can only write 音乐 and obsess over Christine for so long, right? What else is a Phantom that's hanging about the opera to do, besides use up some of his endless time creating a mini stage and singers? The switching heads is mainly an slightly-overly theatrical way of symbolizing that he wants Christine instead of Carlotta to sing the Countess.
And yes, it is a little creepy... hey, he's a creepy guy. It works.