Toe:
Toe is the relationship of the tires as viewed from directly above (or directly below, as the street sees them). 0 toe will have the tires absolutely parallel when rolling down the street. Most factory alignments use toe in, the tires are usually pointed in ever so slightly (usually 1/16th of an inch, give or take). With toe in, the steering needs to be turned enough to cause both tires to "point" the direction you want the car to go (as you turn the wheel, one wheel will remain pointed straight ahead while the other begins the turn....turn the wheel a little more and both wheels begin to make the turn....toe in tends to add stability to a vehicle....it makes the car less "twitchy"). With 0 toe, when the wheel starts to turn, the car will begin to turn as well, both wheels begin the turn together. 0 toe tends to make a car much more willing to initiate a turn. Toe out will do the same as 0 toe, but it goes a step farther...since the wheels are already pointed slightly out, the car is already "trying" to turn, it makes a car even less stable and more willing to turn (some cars will become very "twitchy" or "nervous").
Camber:
Camber is the tilt of the tires as viewed from directly in front of the vehicle (if you take 2 tires and stand them up in your garage and lay on the floor in front of them, they will likely be parallel, both standing vertically, which would be 0 camber). Negative camber is when the tops of the tires are closer together than the bottom of the tires, positive camber is when the tires are closer together at the bottom than the top (negative camber is / \, positive camber is \ / as the tires are viewed from the front) As a car begins to take a turn, the forces acting on a car begin to cause "body roll", during body roll, the front tires will begin to change the way the tire sits on the ground. As the body rolls, the contact patch on the road may be reduced (as the tire tilts away from the ground), to combat this, we add negative camber to the front suspension. Negative camber will help reduce the tendency to wear the outside edge of tires on cars that are driven hard through the corners. Negative camber will also help keep the contact patch of the tire flat on the ground during body roll. If you increase negative camber, you will begin to sear the inside edges of the tires when driving around (non-aggressively), since there is slightly more load on the inside edge than there is on the outside edge.
Castor:
The best way to describe castor is to look at a front wheel on a shopping cart, the carts front wheels stay straight due to castor. Castor is the angle of the point that the spindle rotates on when you turn the wheel. It is not straight up and down like you may think. The tire actually turns on a "tilted" axis. If you turn your wheels all the way to one side and look at them from in front of the car, you'll see that one is tilted in, and the other is tilted the same way (\\ or //), Now, if we have negative camber (with the wheels straight), how did we get negative on one side and positive on the other? That is castor at work. As you move the axis that the steering pivots on, you can get the steering to add negative camber when the wheel is turned. More or less castor will change the ultimate amount of negative camber "seen" by the road surface. It is a delicate balancing act....too much castor, you will have very "heavy" steering, too little and you'll lose cornering grip.
