Oil leaks - I think all German cars leak oil somewhere, the only question is to what extend, i.e. how much. The most valuable thing on your car is acltually pretty cheap - it's called a dipstick. If the oil is leaking a t a very slow rate, you can drive it 3,000 miles without ever having to add even a quart, i.e. you are fine between oil changes. So I'd say monitor the leak first and see how mych you are really losing, or if this is just typical Benz "wetness" on the pan.
Valve seal burnig oil - I'll leave this to others, but I think that could be more serious.
Fuel actuator - are you talking about the fuel distributor? If yes, that's more serious. Otherwise, I'm lost, but I can tell you that many of the parts that go on the fuel system aren't too terrible (except for that distributor).
1989 560 SEL (black/black)
2001 Audi TT Roadster (silver/grey)