W126 260SE 6-cylinder manual with FPR, Petrol Fumes, Overheating problems
 

Hallo all.
I'm new here and I've gone through as many of the threads related to my problem as possible.
I got a 1989 W126 6-cylinder Manual 260SE passed on to me. It had a Fuel Pump Relay problem and I got a replacement from a salvage. The current one works fine I guess. The original was a 0035452405 but the "new" one is a 0035452005. The only problem I've noticed so far is that the red-line is now below the original 6000+; approximately about 4000. Will the use of this relay bring about any damage to the car?
I also noticed something else especially after refueling. While moving, there's usually some strong petrol fumes in the cabin. What could be the problem?
The car also overheats. I'm not sure this is overheating because the gauge is usually about 100+ but never in the red zone. I noticed that the car leaks water (coolant) from the puddle I get while parked, especially while parked at a slope. This I could also I guess this I'll look into to trace the leakage point.
My handbreak doesn't work too. How do I fix this?
Also, other minor problems like the seat-belt warning light, the temperature gauge and the clock which don't work.