I wouldnt really count them as common problems, but after 15 years some of the sensors are ready for replacing. The original knock sensors are probably cracked, and the driver's side one is a bear to get to. The O2 sensors go bad too, they're $100 a pop for the Bosch units.
My MAF sensor went as well, so when you custom make your intake, don't use an oiled air filter, use a dry filter like an AEM cone style. Oh, and don't switch to synthetic oil, only dinosaur for this beast
Rust really won't be a problem unless she was abused, I was reading in the R&T guide that they coated the undercarraige with zinc and engineered good draining to avoid moisture building up anywhere, so the SVX resists corrosion hardcore
All-around tinting is gonna run you $200-300 - the car has ten panels of glass! You can get a good lowering spring or coilover setup from the motorsport warehouse, not an option for me in the boondocks as she's too low as it is!