2 different size torsion bars? what is preload?

I'm not even going to answer the first question.

Sounds like you did it right to me, as I just did mine and yours sounded the same.
There really is only one way they can go in and hold the car up.

The 30 degree thing is the offset from one hex on the end to the other.
If you notice, the bars will not lay on a flat surface without one of the hexes sitting up on one of the ridges. (should be about 30 degrees different than the hex on the other end) which is the factory offset.

That help?