Dizo,
Good luck with the interview. Best advice is just be yourself, and play nice with the other fellas during the process. You will be part of a group, and do a whole bunch of group activities. They just want to see you get along with others really. Try to have a good time while doing it all. There is a lot of info on this site re the whole process..so a search will help.
I think we have a dozen or so Pilots who are French. There are quite a few French Cabin crew.
Quite a few Pilots are commuting between Dubai and other countries where their families are living. This can be difficult, as flights during most of the year can be full, and rosters make getting enough time off to get home a hard thing to achieve. But it can and is being done. Things change pretty quickly over here. I think commuting is harder now than what is was a year or so ago, what it will be like in the future I would not like to guess. There are soo many factors which will effect how it goes (what fleet you are on, how many hours you fly per month, which destination you want to commute to etc) that the results will differ greatly between those who do it.
Good luck.
Don