I will try and answer one of the questions for you.
Who's gonna be behind the blackmail?
The blackmail is connected to the photoshoot but is there a connection between the Photoshoot and the Schoolboard?
After the conversation between Janet and Wanda it would seem that Wanda took a bigger paycut then the rest of the staff so are these two things connected?
I think this whole income reduction story can only be a plot development excuse for Wanda to find herself a part-time job in future updates and nothing more behind it. Teaching at the Randy's school, helping and caring for old Gavin at home, singer in a restaurant, a model - all this possible events needs a background reason. Paycut is a simple but most reasonable of all explanations.
Why Wanda took a bigger paycut then the rest of the staff?
Why not? She's not an ordinary teacher after all.
The higher the position, the higher must be paycut
And 1 more thing.
What if someone from a Faye modeling agency sent Wanda that letter reproaching her not for the photoshoot, but for the fact that Wanda was alone in dressing room with Vincent and had (according to the sender of the letter opinion) an intimate connection with him?
After all, Wanda will receive that letter only if she allows him stay inside if i remember right?