the VIN no. is not used in japanese market, in place of that the car serial no. punched into the metal is used and is also found in 2 locations - one being the B pillar.
For the steering leak - best repair it now as you will not like it later on, You say the oil is dripping ON on the boot, which means that the rack itself is not leaking but something above it, Get the car on a lift and get a strong light to see where the leak is originating from. And please dont use ATF in that steering system. Locate proper oil and use that once the leakage is stopped.
Its a nice car - but the engine is not smooth, so bear with it. The smooth engines are the 6s. I would suggest to fully inspect the undercarriage when its lifted. use a pry bar and try to move the bushings and linkages, if you feel sloppiness you need to replace that part. Usually the entire suspension bushings are rotten by this age if not replaced and mostly due to owners taking pride in saying.
"no maintenance mashAllah, only oil change and filters replaced"
That is a sign of a disillusioned owner who is trying to load his headache on you. These cars wear out slowly to the point of people not noticing their deteriorating ride quality, They have a special taught and controlled drive - not wallowy soft like people think. The power steering is also a bit hard along with the foot pedals too - it always has been in every MB
check the coolant in this car, it should only be using genuine MB coolant (BASF glysantin 5) or similar. its a yellow colour coolant and is very oily to touch. It protects the engine and other plastic parts like the radiator, heater valve and aux pump.