I think you will find out about the Grade what abc150 referred to during the interview with HR. QP already has a price tag in their mind for your position based on your experience. I guess QP already provided you with a range of possible salary. If you are chosen most likely you will be offered the the starting range + 1k (max 2 k) and most likely they will not modify their offer. benefits will be same just like others for that job grade.QP has a very generous benefit plan. There is no way QP will negotiate about the benefits.

Good luck and don't forget to do a small research about Qatarization. :)