Fixed Speed Cameras - Yes, one of the weeklies (Auto Plus?) has a map of them all.
Mobile Cameras - Yes, the Gendarmerie use blue or white unmarked cars with digital cameras concealed in them. Look for dark panels next to the rear number plate and dark tinted windows. French police cars also have a different number plate format form the usual nnnn aa nn format.
Also pay attention to traffic coming the other way flashing headlights - speed trap ahead. Another to watch out for is a speed trap immeadiately after a speed trap. I've counted over 20 on the same road. You think you've passed the trap and are home and dry - when there's another. You will also find them at night. I don't want to put you off, but keep your eyes open. Last but not least, don't get caught doing 200km/h they can ban you on the spot! TAXI!
Autoroute Tolls are generally only at join and exit points, except where the road becomes a city ring-road (free) when you'll find them at the start and end of the free bits. Yes, stop for a coffee and gain time back. Watch what the bikers do. They stop after collecting the ticket from the toll-booth, have a smoke and then thrash off down the road.
98 octane unleaded is available from supermarkets, so you'll never have a problem.
Good idea is carry a spare 150€ just in case because on-the-spot fines have to be paid.
Finally, expect crowds around your car. Supras are VERY rare in France. My main dealer had never even seen one before I turned up one day... "We're not worthy, we're not worthy" etc.