I think it's pretty clear Jo knows Ryan. She also knows that Kate knows Ryan. In every scene they've all been in together Jo makes a point of dismissing Ryan - to try to avoid Kate recognising him?
So Kate has clocked Ryan and has probably ID'd him. Jo fears Kate realising this which - to me at least - suggests a prior relationship between Jo, Ryan, the OCG and institutionalised corruption in the force.
I'm guessing that whoever recruited Ryan is in on whatever's going on too.
I'm still not sure if Kate is brown-nosing Jo or if Jo is brown-nosing Kate. 
I don't think Steve is hoping for anything romantic with Steph. He's clocked Hastings' relationship with her and is suspicious of him. I think Steve's been promoted to keep him onside (or to ensure that he doesn't take up Jolly's offer). Ted's behaviour in S5 was highly suspect - Kate and Steve both know this: i think they're all capable of corruption though.
I'm hoping that this series doesn't turn into "bent coppers by numbers" but I think we have to acknowledge the potential for bentness in everyone. Including Wise, who I think could turn out to be the bentest of all.
She's been promoted, has no time for Ted, can't be a Mason. She's close to Sindwani. Too close, or just close enough to avoid scrutiny?