Don't take my word for any of this but when I moved here from Dubai. Your vehicle had to be under 5 years old (not sure if it applies still)
If your firned bought his vehicles new, he should try and get the original customs certificate (Certificate given to dealership stating the traditional 5% Customs duty) this is not compulsory but if you do not have you end up paying 5% Customs duty. that could be a lot of money for an expensive vehicle.
Apart from that. Try and bring these vehicles in a container (not by road or open air) it will guarentee that your vehciles are in a good state when they reach you here, you can also include all your cargo in the same container.
Once the vehicles are here you need to be resident to be able to register it, if you trust eachother you put everything on your name. (Shipment, Car, Motorocycle and the whole move) on your name it makes things easier then you have to transer to you.
When vechicles are out do not drive them, arrange for a two truck. Get them insured and then registered, then you will get number plates for them.
Good luck