Question: Why does York suddenly fly backwards on the tower?
Corrected entry: Susan Plummer is in Denzel Washington's flat when he arrives home but there is no explanation as to how she got in.
Correction: Susan is a former DIA operative. The implication is that she used her skills to get into the apartment undetected.
Also of note is that McCall is aware that someone has broken in and reacts to it as if it is a threat, until he discovers it is Susan.
Question: What was the name of the book McCall gives to the kid to read as part of the deal to paint his kitchen wall?
Answer: Native son.
Between the world and Me by Ta-Nehisi Coates. Native Son is the book on the shelf that hides the button to the panic room, which also happens to have been adapted into a movie which the actor that plays Miles stars in.
Answer: Extremely high winds from the storm. He was relatively protected lying down but blew backwards when he got up.
A cable on the roof grabbed him and pulled him back due to the wind velocity.