Was also think about the whole role Mr Roque plays in all this.
So in the dream in the beginning we see Rita/Camilla taking the same sort of journey up MD as to what Diana took in reality, same Caddie, same number plate etc, so its a fair bet than in the dream Diana has her heading to Adams's place. She has a bag full of money (its not the hitmens money in a DKNY bag), so it must be hers, money she earn't from being on the game maybe, though it could have come from the mafia brothers.
Anyway Diane in her dream doesn't want to acknowledge that you sleep your way to the top so she invents buying your way to the top, hence the money.
Mr Roque doesnt want Rita/Camilla to meet Adam, much the same way as Diane wishes Camilla didnt meet Adam, so he arranges to kill her off.
The reason why I believe Mr Roque doesnt want her to meet Adam is because he may have some infatuation with her (like Diane).
Anyway none of this explains why it should be Mr Roque, well the telephone conversations may offer a clue, girl still missing (why Would Roque be bothered about it unless he was involved), then Ed the hitman saying he is doing some work for a guy and seeking out prostitutes via the black book and the girl at Winkies.
Also further compounded in the final call when a red light (brothel) next to an ashtray with cigarettes where one clearly has red lipstick (we see Camilla smoking at the dinner party, so is a smoker and wears heavy red lipstick).
Mr Roque is fed information by the police, because if you see the unaired pilot, there is one initial phonecall missed out, where Roque picks up the phone says thankyou then dials out - I believe this to be the police saying she is still missing.
i just cant tie in where the mafia brothers come into it and why ' the girl' is so important, Mr Roque doesnt even know her, so I feel the acquaintance is loose and they don't work for him like Ray does.
However the fact Adam is recasting suggests that something happened to the original actress (Camilla maybe), but then the above would become a bit blurred if that was the case, i.e why would Camilla have money with her!!