Sometimes I just want its door facing left or right

No, you can't rotate the exit door. I made it so the door can only be south, otherwise you wouldn't be able to see where the door is.

Yeah. I overlooked that. And , about power limit inside the factory, if I have enough power supply, does that mean I can set the all limits to 100GW anyway

Yeah, you could do that. Just be aware that if you set your limits to 100GW then each factory will have a whopping 3.3GJ buffer that needs to fill up first, and that filling this buffer has priority over absolutely everything else in your electric network because it's that big and Factorio works like that, and that the buffer gets erased every time you pick up and replace your factory building.

thats great, I dont need to calculate the power consuming of each factory. Low power? Build more lear power plant