Seems like some excellent advice so far. The only things I would add are -

In the event of a breakdown which is fairly unlikely, get in to a mindset that it doesn't need to be fixed instantly, its okay if it takes a day for someone who can really help to come along, its not like the Uk where you can phone the AA and have a response in an hour, but if you get into a mindset that its okay for it to take a bit longer and just enjoy where ever you are, however odd it might be. We have had some quite cool experiances in places that I would never have chosen to stop but have done due to mechanical issues. If you get into this mindset then its take loads of the stress away. Equally not getting hung up on keeping to an timetable. Obviously have enough supplies to be able to camp for a couple of days - eg water, food, etc. Chances are it won't happen.

Regarding the wife and pistes, well we've been trans africa, we've been back to Morocco since plus loads of other offroad experiances from Norway to Australia and the wife who is brilliant with the general overlanding thing, absolutely loves it but still starts stressing when the vehicle goes offroad. Even onroad I noticed her praying in the back seat in the Alps only last week as we inadvertantly four wheel drive drifted on a 180 hair pin bend on ice. We still go and do it and she chills out after a bit.

Have fun.