Diesel Leak & Some Smoke W123

Hello,
I have just bought a 1979 300CD. Overall I'm very happy with the car, but I have found two problems.
I have found that the car leaks diesel, especially when I apply pressure to the gas pedal. The car also leaks a little when it is simply parked. When parked a small puddle forms behind the rear right hand tire. I have discovered a trail of diesel on the side of my car leading from the fuel tank door to the bottom of the quater panel on the outside of the car. When I open the fuel door, the area inside is always wet. I have also found a small trail of diesel fuel on the right side of my trunk. This trail starts near the location of the fuel door. Please reply with any comments on this problem.

My second question is whether or not smoke is normal when accelerating in diesels. The smoke coming from my tail pipe is gray/white in color, but is not visible when the car is simply turned on. Please reply with suggestions on how to reduce or eliminate the smoke.

NOTE***I would also like to add that the oil pressure is always at its max whenever there is any level or pressure applied to the gas pedal. With no pressure added to the pedal, the meter needle drops to about the half-way point on the meter. Is this normal?****

Thanks in Advance,
Mike
18 years old
(Student/ part time employed)
Los Angeles, California, USA