I will help you with what I can.
I believe (I am pretty sure this would apply to your car), that it will start in second gear, unless put into kick-down. And yes, the Revs are normal. My 1995 C-class is the same way. The transmission sounds fine to me.
As for the oil leak, it could be the head gasket, but I am not sure if this was a problem on that car...
Others will provide more valuable input I'm sure, but for now, I think your transmission is just fine! Good luck.
2006 E350 w/ 155k miles (Daily Driver)
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)