First. Run to Auto Zone & have the CEL codes read for free. Perform a search of these boards for those codes to find out what may be causing them. This site has saved me HUNDREDS of dollars and lots of time. The search feature has made the difference between having a PITA junk car and a FANTASTIC family sport sedan for me. The Duratec will flat out FLY!! Give it a shot - really.
Answers to your questions itegrated below.

Originally posted by chem_eng:
I'm a newcomer, so please be gentle! I just bought my brother's '96 Contour Sport w/ 2.5L V-6 with automatic transmission about 6 months ago. It's all stock. The "Check Engine" light comes on occassionally, but I've given enough money to Ford to learn that that is due to a worn out catalytic converter. Now for the questions:
1) Is this a Zetec or Duratec engine?
Duratec
2) Are there any after-market headers and exhaust systems available for this car?
Yes, MSDS makes a nice set of headers for the Duratec. There are also cat-back exhaust systems available and high flow Y-pipes, on & off road. The cat backs I know of are made by Basanni, Bosal, Borla, Bruellen. The web site for BAT (British American Transfer) has a special going for the Bosal system with a Y-pipe.
3) What about cams, lifters, pistons, valve springs, etc. for this car?
You can pick up SVT Cams, but they'll be expensive.
4) What about turbos?
Street Flight
5) What about heads?
Dunno
6) Any Nitrous Oxide kits for this car out there?
Couple of systems available. I'll let you search for those.