Everything you've been told here is correct. I would just add one further thing. Everyone can make mistakes, even French vets, so when your vet has dated, signed and added the time (in 24 hour clock), to your dog's passport, double check that everything is correct. My daughter and son-in-law, didn't, to their cost and when they got to Calais after a seven-hour drive, they discovered that the vet had dated the passport incorrectly. She had put the date at 12/11/08 instead of 12/12/08. The authorities are totally inflexible so they had to overnight in Calais, have the vet's examination etc done in Calais the next day and then wait a further 24 hours before they could return to the UK. There's not a lot to do in Calais in the middle of December!

Incidentally, my passport was free.