I don't think it's wise to take up a new opening 2 weeks before a tournament. Unless of course you consider the tournament a learning experience and you're not really fussed by the result.
Preparing with the French
The french is not a difficult opening, he can learn it, even if the tournament will be 2 weeks later. (And you are a diamond membership player, I guess there are some videos on the french defense here...)
Dangerous lines? The french is usually closed, (you can play it closed anyway) but the open french is not dangerous either.
If you want to play closed french:
In the closed lines, Black usually attack on the queen side, and white on the king side, I dont really know the opened french.
I'm really not new to the French. I'm just trying to get back into it. However, I think I agree with you, Plutonia. It would be unwise to switch. I would still appreciate advice on the subject though because I think I will switch after the tournament.
I plan on using the French in otb play for the first time. The tournament is in about two weeks. I was hoping for some advice from experienced French players. It would be great if you guys could post some obscure but dangerous lines which I need to look out for along with more general advice to improve my chances of a successful tournament with the french.