I haven't messed around with dynamics very much but I watched a few tutorials and most of what I wanted to do was pretty easy. What I wanted was to have a sphere hit some text vertically, the text flys up, gravity pulls it back down and then it slides down a spline that I have extruded. Every thing is working except the sliding down the spline. the objects aren't sliding down the spline if it is a wavy shape. If it's just an arch it works or if i get rid of that and just put a sphere there it works. Ive attached the file to show what i'm trying to do.
The Dynamics Body tag on the Extrude needs to have Collision/Shape set to Static Mesh (or Automatic (MoDynamics)) - when it's the default 'Automatic' it uses the bounding box of the object - which is a cuboid which surrounds the object - static mesh uses the object faces that are there, it's slower to calculate but it will give you what you want.