hi,
Please Please Please make sure you get the fines cleared before u make the transfer. It so happend to me that when i too bought a car advertised from a QL poster, that there was a fine on the car. But the moi website did not show it wen i bought the car. After 3 months i got an sms from moi saying there is a fine on the car. but that fine was for a violation done by the previous owner. this happened because the traffic violations notification system was not updated. I had a tough time convincing the guy in madinat khalifa police station that the violation was done before i purchased the car. Finally the fine was transfered to the previous owner.
I didnt recieve any reciept on cash payment to the owner. Apparently it was a trust deal. The transfer formalities was entirely done by the seller, so im not too sure about the formalities on that front.

Good Luck.