You lucky lucky lucky buggers! I wish I was going on a trip like that! I speak 6 languages fluently - Urdu, Punjabi, Hindi, Japanese ( thus, I can read chinese characters) and English of course! I have travelled in several of the countries you are travelling in!!!! If one of you gets sick - call my cell!
My advice, keep plenty of cash, water and puncture repair kits, as many spares as possible!!!! Also, a decent tow rope and some boards to get you out of any ditches you get stuck in!
By the way, not sure if you guys have travelled in China but the roads are much better than India and some of the other countries you are travelling in!
Lastly, suggest that you keep a few cans of petrol! Will have a think over night and think of some other essentials!
Migration info. Legacy thread was 89500