It does not sound like this car had competent service, either by a dealer or an independent. The SRS light should have been addressed, it may not even be in the car. The oil leak is probably from the timing cover on the front of the engine, a very common problem with this engine. There is a new sealer that MB uses that now works. The dealer or good independent should have no problem with this.
Check that the trans. has been serviced on schedule. If not, then it should be checked and serviced.
Also check the engine wiring harness for deterioration. Use the search function of this site for the complete description of this problem.
Inspite of the "gloomy" comments, they are great cars. I purchased a '94 wagon last year and love it. Ed