Help Buying 2003 S430 4MATIC!

Hi all, I posted a thread in the technical section, but no one seem to answer, so I am trying in this section.

I have a 2000 ML430 with 114,000 miles and it has gone through all the common problems. Overall, it's been a great SUV and mostly reliable!

I am thinking of purchasing a 2003 S430 4MATIC. I want to know what are the most common problems with this vehicle. Also, can I do the oil changes, brake pads, etc myself like the ML? I heard the air suspension goes out a lot, how much would it be to fix that?

Please help before I purchase, thanks a lot!!!