Stefan Hi. I haven't planned this trip myself as I am no longer sure whether it will go through. Circumstances/plans change as well as finances and time frame. I may still do it if I am with the right people and the schedule works. If I was to do it I would be more inclined to do it during summer 2012.
Anyway check out http://www.seat61.com/Trans-Siberian.htm for a lot of good information on how to do it. Personally I planned on zigzagging my way around Europe on trains before starting the "journey". Slowly take the Trans-Siberian, stopping at the major attractions along the way for a rest/sightseeing. When I am in China it would start to become more of a "go where you are taken" type of travel (it is Asia after all). Maybe ditch trains when in Hanoi and motorbike to Saigon (its a very popular adventure and looks great). The rest would work itself out pretty much as planned.
I think the total cost of trains to go direct (as in no extra trains in Europe) is around 650 pounds. Depending on whether you would get a Eurail/Interrail would increase the price. It could be a relatively cheap trip if you were to Couchsurf for a bit in Europe etc.
What canal joins the Red and Mediterranean Seas?
... to be completed