Funny fact : since some time now the FFMC (French motocyclist association) negociated the toll fees which are way cheaper than in car.
Not-so-funny : if you have a Visa Electron or the equivalent with MasterCard, card won't work with highway machines.
For the speed, if you have a foreign-plated vehicle, automatic speed traps won't work, manualomatic ones (car parked with a speed trap inside) neither. You only have to fear the "Gendarmerie" (military police) which will chase you using FJR 1300 / BMW R1200RT or Megane RS. (if you're over 150kph). Under 180Kph, foreign licence holders will only get a 90 Euros fine, which you have to pay immediatly in cash (y'know finances Pastis and peanuts)
Fred, you might have seen foreign-plated cars going quite fast on the highway, especially arriving to Toulon, this explaining why (yellow front plate usually)