Mongolia West to East

After a 2 month trip in Southeast Asia with my wife (I'll publish some pictures later on) I got really motivated to do another trip.
First time for me that I took so many holidays and so far away. So after the trip I started immediately to think about my next adventure. And then it came Mongolia. A lonely corner of the planet with a really wide landscape where you can be alone.
I'm planning to go with some friends and not just go there, but traverse the country. I'm gathering some info, so if someone has useful info please let me know.