Some items, like "Dust Motes," provide bonus points but aren't necessary for the ending.
Enter the symbols found on the Hallway Mirror earlier.
Locate the three missing journals (Red, Green, and Blue) scattered in the Kitchen and Dining Room.
Use your flashlight on the ceiling to reveal a 4-digit code. This code typically opens the laptop on the desk. The Master Suite
Small keys are often hidden in wastebaskets in the Kitchen and Study.