If you are doing an essay or a test for example- it should only be 1. if your homework is only writing a main idea paragraph you can do so, it’ll make it easier to read and correct. however it also depends on the grade or teacher. if you’re in a higher grade or have a strict teacher they may not allow you to do that.
The open window and the landlady both show the creepy experience by the main character. Both add to the experience with imagery and (should I continue?)