Rented this little nugget in Germany last fall. Peugeot 2008, turbo diesel, 6-speed. Nice little urban cruiser. French cars don’t suck these days.
I looked into the international driver's license before my trip that went through the Netherlands/Belgium/Germany. It appears somewhat hit or miss, but most countries only require it if your DL is from a country that doesn't use the Roman alphabet. I decided not to bother and it was not an issue. I'd check specifically for French rules.
Lance discipline is better, but I don't find driving in Europe particularly fun. Even the Autobahn tends to be pretty slow outside the de-restricted sections.
I've spent a lot of time driving in the EU and never had an issue with my regular drivers license. Now I've moved to Germany and my previous state (not all US states have this) has reciprocity with Germany so I'll only have to take the written exam, from what I've understood. The places I've driven (mostly Romania and Germany).. the road rules are the same and it's been easy for me to handle myself on the road. I have no issue getting rental cars with my US license. I've rented cars in the EU about 20x over the years and nobody at various rental car places says a word about it.
Having grown up in Europe (Netherlands, Belgium, France), France really isn’t any more or less difficult to drive in than other Western countries. Just pay attention to speed cameras and possibly highway tolls, although I doubt you’ll encounter those with your itinerary. Like others have said: don’t hog the left lane, and don’t be offended/surprised if you have someone behind you with their left blinker on for a long time, as that has traditionally been the way the French signal an intent to pass. Also, and this is important: unless otherwise indicated, traffic that comes from the right has the right of way.
Count on there being more pedestrians and people on scooters/mopeds/motorcycles than you’re used to, and count on them being fearless and split lanes whenever they can. They pretend you’re not there, so you should do the same—drive a little assertively.
It may all seem a little more chaotic, but there’s a method to the madness. In a city that may mean that everyone wants to be the quickest, and in the countryside that could mean that no one is in a hurry and just enjoying their day. As long as you’re able to adapt to the “mood” of the locals, you’ll be alright.