Vehicle Question

#1 One of the easiest ways I can think of to do this, would be to derive your trailer from the wheeled vehicle class, and "attach" it to your truck (which again would be a wheeled vehicle). You you use a node in both the trailer and the tractor unit to define the attachment point.

As for implementing the actual contstraint, I you would have to implement some form of 3dof angular constraint which would apply the proper forces to both bodies. I don;t have any easy examples of this sort of thing at hand, but I'll see what I can find if you want.

#2 It might be an idea to take a look at www.ode.org to see how the constraints work there, and see how you could learn from the constraint code and use it in Torque.

#3 If you don't know C++, would it not be better to start on a much smaller game... give it a year or two then look at making your truck sim?