Why are we told the safe combination?
Because we need to know for story reasons, to be able to get the car key and the laptop.
She left college because she felt uncomfortable after leaving the restaurant and is worried Burke might do something to her.
What's the story behind Quinn's drug operation?
I'm sure we will learn more details in future episodes.
Why did Bella unlock the locked door and forget to lock it?
Because humans make mistakes and forget things. In my opinion it indicates that she enters the room relatively often. If you only unlock the room, let's say, once a year, you probably won't forget to relock it.
Who do the test answers belong to?
I'm sure we will learn more details in future episodes.
Why did Cathy, someone with a math PhD, become a corporate trainer, and why did she break down multiple times after saying she was fine?
Because she wanted to get away from teaching after the photo leak experience and because it probably pays well.
Because people often lie about their mental state.
Why and how does the restaurant offer free tuition?
Why? As an exchange for sexual services. How? I'm sure we will learn more details in future episodes.
Because as an ex-girlfriend/childhood friend she offers something none of the other girls in the game can offer.
Why is a hardened drug dealer who laces coke with fentanyl, drawing symbols of weasels on their face, complete with a children's' book explaining his creepy/retard-level thinking, will make us give a flip?
We don't know if Rox laced the coke. Because he liked the meaning of the symbol. Because low-level drug dealers, especially when they are addicts themselves, don't tend to be the sharpest tools in the shed.