^^ Habibi I will do my best to provide you with maximum info.
I dunno about Dubai but in saudi u will find 100s of gas stations scattered along both sides of road. As you already know 'Muhatta' and 'Istaraha' ..... about fuelling you dont have to specifically choose a gas station, all are good and fuel quality is great. I had a rental car and I filled 'MUMTAZ' which is '95' grade petrol just to check the performance and fuel average but then in Saudi no one really cares about average coz of petrol being dirt cheap, rather sand cheap .... 
Everyother gas station has 'Pakistani Hotel' boards and you will find friendly pathans there ...... for istaraha (motels) look for AlDress pump stations, they are of good standards. Dont hold your breath for an outclass motel besides Makkah highway as there is none cuz mostly these hotels are max one or two night stands. You will find 'Mikaniki' (Mechanic), 'Kaharbai' (Electrician), and 'Mutjir Ataraat' (Tyre shop) almost on every gas stations, other than the haunted ones
so dont worry about any mechanical issues.
My practice is I try to grab the number of nearest Recovery Truck available from the last gas station I get my tank fill up. This way you know how long will it take in case your vehicle breaks down.
You can easily buy (as per consent) ehraam for gents especially, belts, chappal, purse, etc. so I woudnt worry about those.
Last but not the least, make sure you keep at least two cell fones, its easy to get lost in crowd and cell fones are of major help. Keep minimum cash with you and Alhamdulillah in Saudi you can keep your belongings in your car without any doubt. Not to mention but DO NOT LOSE CAR KEYS ...... thats the last thing you want.
In Makkah make sure you park your car at designated car parking, otherwise the 'Kind Saudi Police' will tow it from there and you have to spend hours and hours to get it back. In Madina you will be amazed to see car parking lots. Tons of them there and easy to get.
Ok brother now its jumma prayer time.
Later