Animation for physics driven tank track

Hi,

I am working on a physics game in Unity3D and in that contect I need some animations for a tank track.

I need to produce an animation where I move ~10 cube shapes along a closed curve. The Idea is that I in the game engine create rigidbodies and constrain them to these boxes. The boxes should offcourse be evenly distributed on the curve, follow it around, and follow the curve of the line.

I need all this in one looping linear animation animation where the boxes take a full trip round the track.

This should hopefully give a more realistic looking tank drive.

I am not sure if I need it as an armature or just animated boxes.

I have been playing around with different constraints, but I have had a hard time getting offsets on the individual boxes right, and following rotation on the curve.

How would you recommend to proceed? (What constraints and how do I bake keyframes)

Thanx in advance

Jesper

P.S:
A quick side question. How does blender handle multiple animations. Can I create more than one animation per blend file or am I forced to have a blend file for each animation I need.