Anybody done it?

I'm starting to think about my RTW a year from now (award trip), and think this would be a cool thing to build into it. I'd want to do Beijing-Moscow, and then perhaps take trains on to visit friends in Poland.

Questions:

1. Have you done it? If so, what would you do or not do if you're doing it again?

2. Is it possible to stop for a night or two en-route, and catch another train a day or two later? If so, what stop(s) are recommended?

3. Who did you book through? I see both very expensive options with tour companies, and have read about people who booked first class on the regular train and did fine for much less.

4. How long did the trip take you?

5. I've got a cousin in Alma-Ata (Almaty), Kazakhstan. Any idea how crazy I would be to attempt Beijing-Alma-Ata-Moscow?

Thanks!

JP