have the hotel order a taxi the day before. There will be a little advance charge tagged on (5€?).
I believe that the approach fees were eliminated when the fixed airport rates became effective. These fees were a huge problem as these costs were often inflated by drives to include a kickback to the hotel doorman for having summoned that particularly driver. I think that these extra fees are now illegal, at least on fares to the airport.
You say the trains are frequent and no need to reserve a specific train? Or are you talking about the taxis at CDG?
The Gare St Lazare trains to Normandy are generally open, no reservation required unless you want one. You can reserve a taxi from CDG to Paris but a reservation negates the fixed fare, you will be charged the meter plus wait time. There is no need to prearrange taxis from CDG. There are always plenty of taxis, lines of them, ready to pick you up.
There is train service from CDG to Caen. Right now there is one a day which departs CDG at 12h38 and arrives Caen at 16h25. That´s almost 6 hours en route which may not be of interest to many but these schedules change all the time. It never hurts to take a look.
the car rentals at the Caen station close for a long lunch
Lunch time closing of rental car pickup offices is universal throughout France. Only the big airport/train station offices remain open during lunch.
Perhaps others can provide further input on the topic of purchasing TER tickets for the day of arrival.
acraven is correct about pricing on TER trains. Prices can change during the day and tickets can be departure time specific. There can be special prices for those 60+ for specif trains, not to be confused with the Carte Advantage Senior fares which are something totally different. Some of the TER fares can be as low as 15€ and they can be prebooked. Check with the SNCF website.
be sure to always greet every French person with “Bonjour” before saying anything
The French have no expectation that visitors speak French or any part of French. It really does not matter. However, everyone in France expects you to say hello/bonjour before you say anything else. It sounds easy but Anglophones really do not do this as often as we think. Even if you ask something of the maid cleaning your room, start the sentence with hello/bonjour. That also includes saying hello/bonjour to the bus driver when boarding. Some greet those around them when being seated at a restaurant. I always say goodnight/bonsoir to my dining neighbors when leaving a restaurant.
I highly recommend not only having a car, but not visiting Normandy without one
I could not agree more with this observation by PharmerPhil. You are cheating yourself by not having a car when visiting Normandy. Just don´t drive it from CDG on the morning of your arrival after an all night transatlantic flight.
Basing yourselves out of Bayeux is very convenient and quite pretty.
You really want to stay in Bayeux over staying in Caen. There are direct Bayeux trains from Gare St Lazare.