Learn some French. If you want, I can post about 10 very useful phrases to learn--the minimum that you should learn. But you have time to learn more. Just let me know if you want me to post them.

If you want to rent a car, I suggest that you take the train from Paris and rent a car at the train station in Pau. Just remember that driving and parking anywhere the Tour will be is tough. If you can manage just by train and bike, you will save yourself some headaches. It all depends on your touring setup and tolerance for packing light.

Felicitations! It will be a great trip no matter how you get around.