One or two things that have come up on this thread I might be able to help with!
1. Number plate sizes. The size of the number plate must conform to the regulations of the country of registration. It has nothing to do with local law.
2. Glasses or sight correction. If you have an 01 against your category you must wear sight correction to drive that category. If you have an 01, you must carry a spare pair. If you wear contact lenses you must either carry a spare set OR a pair of equivalent glasses.
2a. Beware the sunglasses trap in France. Sun glasses used for ski-ing, offshore sailing , mountaineeering, in category 4 are forbidden for driving.
3. Breathaliser kits carried in France, must conform to NF ( Norme Francaise). EU Norme is not the same thing, so anything you see on electronic devices which says EU Norme, may not necessarily be O.K. in France, and if Monsieur soldier in blue has got it in for you, your stuffed. It is safer to buy the prepacked pair of blow up testers for about 2 Euros from a French retailer, because they will conform.
4. Always carry two breathaliser kits, cos if you use one you must have a spare. It will be an infraction ( €11 or €17 depending on which reports you read) not to carry at least one which is unused.
5. One thing which is frequently forgotten is First aid kits. First aid kits are obligatory in cars, alongside hi viz vest ( one for each passenger and driver) and triangle. Bikes are not obliged to carry the triangle, and the hi viz reflective material ( 125cm2) becomes law for two wheel motorised vehicles ( except mopeds) from Jan 2013. Even though First aid Kits are not mentioned for bikes sepcifically in the law, the law says 'vehicules', which generically covers all forms of motorised transport. It is advisable to carry a small kit on a bike.
It's a nightmare trying to keep up with all the changes even for those of us who live in France. It must be doubly so for visitors.