1. I would either assume that it has been done or that it was one of the few that were "okay" to not have it done. I'm unaware if mine has had it done or not and I have 156k on it.

2. Check the wiring harness behind the battery. Should have a silver label with two dates on it if it has been replaced. The more recent one is the year that the harness was manufactured. If no label then it's original.

3. Not sure.

4. I would get new springs (obviously) and new rear accumulators. SLS should be fine otherwise.

5. It will have heated seats and ASR. ASR can only be shut off for a little while at a time. Mine has it too and I never really bother with it, though there is some way to shut it off completely with a little work.

6. NO. I would assume that running rough might be throttle body related. It's wiring harness will corrode too and the unit will need to be replaced. Used ones are around $300 with good harnesses. You would have to cut open the insulation to see in, but this would be my first guess to rough running on an ASR car.

Check ball joints and lower control arms too. Remember these cars have the "solid" ball joint, and the LCA's are around $170 a piece.

What's that saying about a cheap Mercedes?