1) Saudi transit  visa - You will have to get one thru a local visa agent. You can not go to the Saudi embassy directly.Hurry cuz the embassy will be closing soon if they havent already.

2) Unless you qualify for a UAE visa on arrival , you'll need to get one before hand from the UAE embassy here in Doha. No need for an agent for this,you can go directly

3) The vehicle you will driving needs to be registered in your name.If there is a bank lien etc ,you will need to get a NOC from the bank.Rental cars to the best of my knowledge cannot be taken across borders

4)Valid exit permit - this may sound the most obvious but often overlooked. Once your company issues a exit permit, its valid for 7 days.If you've applied for one already in anticipation of the upcoming holidays,make sure you dont reach the Doha border on the 8th day !

5 ) Directions - The route is pretty straight forward overall. Buy a GPS unit if you can.Its handy once you reach your destination.