caster is the amount that the top pivot point leads the bottom pivot point for a steering wheel. Just like on a shopping cart, it makes the wheel steer into the direction you're already moving. A certain amount of camber makes the vehicle stable, and makes the front wheels return to straight ahead when you let go of the wheel while moving, (something I do all the time!)

Too little (or reverse) camber will make the car drift, and in the worst case, very unsteerable. Too much, and it gets hard to turn the car, and tire wear gets worse.

On a non- steering end, you'd want 0 caster...

no formulas here! <img src="/forums/images/graemlins/smile.gif" alt="" />

Toby