Like Barnsnake said, Caster has the greatest influence on a steering wheel wanting to "self-center" and I agree 4* being a good ball park figure.
With regards to ride height adjustment that is simply a matter of turning each spring platform (assuming you have coil over springs) to raise or lower each corner of the car. Look at your shocks and the body is probably threaded...like it is a large screw...on one end where the spring rides on a "platform" (or nut).
Your Manufacturer should have recommended settings (as measured from the ground to the bottom of your frame).
This makes it eaiser:
http://www.pegasusautoracing.com/pro....asp?RecID=817
If you plan on doing any "performance" driving I would suggest that you consider having a shop that has scales set ride height (with your weight in the drivers seat) so the car is properly balanced.
Ultimately, balance is more important than perfect symetery in ride height.
Good luck!