For Salary negotiation: Tell them to pay you according to your work and pay but If they insist on you mentioning a particular amount,try and find out what their pay package look like and tell them.(e.g can you pay me btw (1.5m-1.8m).
For the consulting firm:In other words,you got the Job through the help of a consulting firm and due to the terms and condition of the consulting firm,you are to pay them a certain percentage of your salary for a period of time.The ball is in your court...............Go and