Mike,

There are a number of CAD programs (or add-ins) for drafting timberframes. Several of them are additions to AutoCAD. I can't really recommend one over the other in this space, but a number of the suppliers set up at each Guild conference to demonstrate their wares.

There seem to be as many different structural analysis programs as there are engineers. Ed Levin uses one program, Ben Brungraber another, and I use yet another one. All are some form of structural finite element analysis program, with the capability to deal with the strength properties of wood. The static distribution of member loads through a frame is really no dofferent than if the frame was all steel. The problem comes in resolving the member loads at the joints using a material with widely (wildly) varying strength properties depending on the orientation of the load to the grain.