trans-siberian railway

I'm considering the possibility of going to Mongolia later this year. I am unsure of the route I would take. One possibility is doing the Trans-Siberian railway, and another is connecting out of Seoul. As I am looking into the possibility of this journey, I will be looking at different routes. Possible countries or places that I might hit along the way are:
1. Irkutsk, Lake Baikal, (Siberia) the deepest fresh water lake in the world
2. Moscow
3. Korea
4. China, Shanghai
5. Mongolia -this hinges on getting in contact with 2 teachers I met and enjoyed spending time with in Malaysia

It's a big "if" at this point. It WILL happen, but perhaps not this year, maybe next.

If you live in any of these places, and would like a visit from an old friend, please contact me. Especially in Russia. I hope to see some friends along the way. :-)